# 2002 Audi TT 225 Compressor / ECT Sensor / Pressure Switch



## thehof2012 (Jun 4, 2020)

Hello!
I owned a 2000 Audi TT 180 about 5-6yrs ago, and recently purchased my dream: 2002 Audi TT Quattro 225! It has a Stage 1 upgrade to the ECU is what I was told. (the car MOVES, claiming ~255hp but no dyno sheets)

I've had the car for just about a week, drove it home 2+hrs with no issues at all.... other than the AC wouldn't run! It had the following codes that I read from the OBDII when I bought it:
-P0140 = O2 Sensor Circuit - Slow Response (Bank 1 Sensor 2)
-P0118 = Engine Coolant Temperature Circuit - High Input (Low Temp)

I have a new O2 sensor (post cat under the car) to hopefully shut the P0140 problem off. I don't have any performance issues to speak of, just a light on the dash at this point.

After reading some prior posts, I've ordered a new ECT Sensor to see if I can shut off the P0118 issue. The car hasn't overheated, doesn't show any issues other than the large radiator fan will not turn on (regardless of engine/coolant temp, AC on/off, ect). It turns freely, but I'm assuming it, or the FCM, or the connector is bad. The smaller AC cooling fan turns on when AC is on, and turns on when AC is "off" but the car is on/up to temp. So, if the smaller AC fan operates as it should, does that rule out the FCM completely? Or, does the FCM have a separate set of resistors for each fans speed?

Anyways, I'm wondering, if I replace the ECT Sensor and I start seeing sporadic readings on the 49C Climatrol compared to the dash pod, that points to a thermostat issue, right? (again, no issues to date, the 49C and dash pod degrees both match or are close so I'm hoping this is a non-issue once ECT is replaced)

Is it possible that a bad ECT Sensor would "shut off" the large radiator cooling fan through the FCM? 
Is it possible that a bad ECT Sensor would "shut off" the AC Compressor? doubtful, but thought I'd ask?

Now on the AC side of things, I brought it home and hooked up a can of freon to check the levels (assuming it needed to be added/topped off). I read the levels, but they're in the red on the can, showing much higher pressure than there should be. I can hear a "click/tick" when I turn the AC on (or have the fan running "econ" and then shut it off), but I can't seem to get the compressor to engage. Using the climatrol system, 20C, I'm showing 13.x volts to the compressor. Does this sound like a compressor clutch issue? If the compressor is getting voltage, it should be engaging the clutch into the pulley, right?

With these issues, I'm just trying to find the best starting point. Once the ECT Sensor is replaced (hopefully next week), I'll have a better idea of what issues were resolved, and/or more information on what/where the other problems are coming from.

Any help/suggestions is appreciated! Go easy on me, I'm new!


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## Hoggy (May 8, 2002)

Hi, There is no A/C fan, both fans should run together at slow speed if A/C is on or coolant temp is 98ish
Both fans should run at high speed when coolant reaches 106 ish.
The fans are controlled the 2 stage thermal switch In radiator, coolant indication is just that an indication & does not control the fans.
Your other fan requires replacing.
Coolant temp gauge is weighted to show 90 when actual coolant temp is anywhere between 82 & 100 ish.
Replace coolant temp sensor with an OEM sensor Part No,	059919501A
Hoggy.


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## YELLOW_TT (Feb 25, 2004)

Welcome  try your questions in the mk1 section should get help there


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## Hoggy (May 8, 2002)

Hi, I have moved your post into the MK1 section.
Hoggy.


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## thehof2012 (Jun 4, 2020)

Thank you guys! Sorry about that, first forum in all honesty (don't know how/why it took this long!)

Hoggy, thank you for your feedback! I'll get that ECT sensor replaced and see what happens. It sounds like a pretty safe bet the larger fan is garbage, your take is my feedback is enough to warrant purchasing a new fan then?

Do you guys have any ideas on why my Compressor isn't kicking in? Could a faulty AC Pressure Switch prevent the compressor from kicking in? Could a faulty pressure switch explain the high pressure reading I had on the LP port?

All fuses have been checked (above the battery as well as Fuse 16 and others in the car). I hear a "click/tick" when I turn the AC on, but nothing goes.

Messaged the old owner, he "claims" he didn't think it had AC since there wasn't an "AC" button..... well ok...... it definitely does have AC. There's pressure in the system so I'm assuming no leaks? (I haven't added anything)

The 20C code on the climatrol shows 13.x volts to the compressor.. I'm wondering if it's just a bad compressor clutch?


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## Hoggy (May 8, 2002)

Hi, A/C prob could be many things a fault scan will help.
A temporary drop in idle speed usually happens if compressor is cutting in.
Failing fan is quite common so probably is, but put 12 volts to it to be sure.
Hoggy.


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## thehof2012 (Jun 4, 2020)

Hey guys!

I got the o2 Sensor and the ECT Sensor replaced last weekend. Cleared the codes, went on a 30min drive (on a very hot day!) and the TT is staying at temp (hit 95C sitting in the garage) with just the small fan running (AC on, other replacement fan is ordered but arriving Friday).

So far, so good. I also ordered a new Pressure Switch hoping that may help my AC to kick on. I checked the compressor, and when "econ" is on, the clutch is stationary (hub/pulley moves), when I turn Econ "off", I hear the clutch engage, engine revs down noticeably, but still.... NO cold air.

The thing has R134a, I gauged it with an older can I had (read high so I thought the can was faulty) bought another can and it has the same reading. This makes me think the pressure switch isn't allowing high/low to fluctuate?

Does anyone have knowledge on this thing? I checked compressor voltage (20C) on the climatrol and its like 13.9v so it should have power. clutch is stationary when it should be, and moves when it should too, so I'm hoping (praying) the compressor is OK? No leaks, have pressure.

Is it possible that a bad larger fan (hopefully being replaced this weekend) could be causing the compressor to cut out? Doubtful, but hoping someone here may know?

Just trying to eliminate potential causes. The thing runs great!! I read somewhere about needing heat tape/wrap over the pressure sensor since it was thermo-something -- any word here? Is it worth trying to wrap/protect the G65 sensor, in an attempt to get AC back?

Could someone be able to walk me through what hoses should be "cold" and what should be "hot" when the car is on, AC is on?

Any help is appreciated, you guys rock!


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## PlasticMac (Apr 25, 2017)

A VCDS scan would probably help you pinpoint the problem(s). No cold air from aircon could be the control flaps that control flow and mixing. VCDS will flag such errors.
Might be a member locally who could help, or buy a KKL lead on ebay (£5) and download the official free version (VCDS Lite) from Rosstech website (https://www.ross-tech.com/vcds-lite/download/).
Welcome and good luck.
Mac.


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## classexa (Jun 7, 2020)

Borrowing this thread. I've the same problem. None of my fans are running. The fuses on top of the battery seems fine. Also fuse 16. Replaced them anyway. Can low refrigerant cause this? Because I'm 99% sure I've next to nothing. Also no cold air. No codes. Can a faulty ECT sensor cause this? I'm replacing that one on Thursday. Have a code on that one and the temp gauge is acting up

Should they both be running regardless of the engine temp? Or when the AC is on?


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## StuartDB (Feb 10, 2018)

I am sure @DavidC will comment as a TT Fan'xpert

but both fans are supposed to run together and removing fuse 15(I think) will make them both run at high speed (only my small one does) <-- been lucky the last couple of years

I believe if only one runs the fault is with the fan - if neither run it can be both the fans or the fan control unit


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## Hoggy (May 8, 2002)

classexa said:


> Borrowing this thread. I've the same problem. None of my fans are running. The fuses on top of the battery seems fine. Also fuse 16. Replaced them anyway. Can low refrigerant cause this? Because I'm 99% sure I've next to nothing. Also no cold air. No codes. Can a faulty ECT sensor cause this? I'm replacing that one on Thursday. Have a code on that one and the temp gauge is acting up
> 
> Should they both be running regardless of the engine temp? Or when the AC is on?


Hi, Both fans should run at low speed if A/C is on or if coolant temp is 98ish & both fans should run at high speed if coolant temp is 106ish.
Coolant temp/fans are controlled by 2 stage thermal switch in radiator.
Coolant temp indication is just that an indication & does not control the fans.
Low gas pressure will prevent the A/C from operating.
Fuse 16 is correct not 15 as previous post
Hoggy.


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## classexa (Jun 7, 2020)

So if I fill it up with gas, they could start running?


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## Hoggy (May 8, 2002)

classexa said:


> So if I fill it up with gas, they could start running?


Hi, If that is the problem & not failed fans etc. 
As they don't run when Fuse 16 removed it's unlikely to be low gas pressure & more likely to be failed fans. Quite common
A fault scan will help.
Hoggy.


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## classexa (Jun 7, 2020)

I removed fuse 16 and they didn't run. So are both fans bad? Can I test them somehow?


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## Hoggy (May 8, 2002)

classexa said:


> I removed fuse 16 and they didn't run. So are both fans bad? Can I test them somehow?


Hi, Trace the plug/sockets & apply 12 volts to the fans, probably easier than bridging the contacts in the radiator thermal switch.
Hoggy.


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## thehof2012 (Jun 4, 2020)

StuartDB said:


> I am sure @DavidC will comment as a TT Fan'xpert
> 
> but both fans are supposed to run together and removing fuse 15(I think) will make them both run at high speed (only my small one does) <-- been lucky the last couple of years
> 
> I believe if only one runs the fault is with the fan - if neither run it can be both the fans or the fan control unit


StuartDB --- Only my "small" fan is working right now -- I haven't seen the large one come on yet. Replaced the ECT Sensor, same thing. I went ahead and bought a new large fan hoping/assuming that's the case here. IF I get the new fan mounted and still have the same issue, I'll know the issue lies either in the FCM or the Thermal Fan Switch, right?

On the AC line of things, I don't have any cold air, I'm hoping replacing the large cooling fan will provide additional cooling to the condensor, allowing the pressures to normalize easier? That or a faulty pressure sensor?

I've got the VCDS Lite downloaded and a KKL cable ordered, hoping to put an end to the nuisances and start enjoying this baby!


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## Hoggy (May 8, 2002)

thehof2012 said:


> StuartDB said:
> 
> 
> > I am sure @DavidC will comment as a TT Fan'xpert
> ...


Hi, Both fans should always run as a pair.
Both at low speed controlled by thermal switch in rad
Both at high speed controlled by thermal switch via the fan control module.
Hoggy.


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## classexa (Jun 7, 2020)

Thanks, I'll try that tomorrow

On another note, this can possibly be the cause for my no AC problem. I've the same code, at least before I cleared it.

https://forums.vwvortex.com/showthread. ... udi-TT-225

But I'm gonna check the gas first


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## Hoggy (May 8, 2002)

classexa said:


> Thanks, I'll try that tomorrow
> 
> On another note, this can possibly be the cause for my no AC problem. I've the same code, at least before I cleared it.
> 
> ...


Hi, Very unlikely. 
Double-check the 40 & 30 amp fuses above battery. The 30 amp is known to burn & cause poor connections.
Hoggy.


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## classexa (Jun 7, 2020)

I've replaced the 30A fuse. Gonna check the 40A again

Edit: Looks fine


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## classexa (Jun 7, 2020)

So I tried to spin the fans by hand. The big one, no problem. The small one I could barely move because it's not straight. It rubs against the housing. So I guess I'll replace that one. What is the small fan for?


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## Hoggy (May 8, 2002)

classexa said:


> So I tried to spin the fans by hand. The big one, no problem. The small one I could barely move because it's not straight. It rubs against the housing. So I guess I'll replace that one. What is the small fan for?


Hi, The small fan does the same job as the larger fan & they should both run together as a pair.
Hoggy.


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## classexa (Jun 7, 2020)

Could a bad thermal switch be the problem? Doesn't that generate a fault code though?

Also, do you know the partnumber for the small fan? I can't find it


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## Hoggy (May 8, 2002)

classexa said:


> Could a bad thermal switch be the problem? Doesn't that generate a fault code though?
> 
> Also, do you know the partnumber for the small fan? I can't find it


Hi, Bad Thermal switch could prevent them running when coolant temp is high but it won't prevent them running for the A/Con. As I said they always run as a pair & one fan doesn't run alone.
Hoggy.


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## classexa (Jun 7, 2020)

Ok thanks. I've now removed the small fan. What is best, a new aftermarket fan or a used OEM?


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## Hoggy (May 8, 2002)

classexa said:


> Ok thanks. I've now removed the small fan. What is best, a new aftermarket fan or a used OEM?


Hi, I'd say after-market. Failures are quite common so a used one will probably have a short life.
Hoggy.


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## classexa (Jun 7, 2020)

Thanks. I just picked up a used one at my local junkyard for $10. If it stops working then no biggie. It was cheap


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## classexa (Jun 7, 2020)

How exactly do I apply 12V directly to the fan? I've the old fan out of the car and I took a 12V car battery. Ran a wire from + on the battery to the pin with the red/black wire in the connector on the fan. The I ran the ground wire from - on the battery to the pin with the brown/black wire in the connector on the fan. Nothing happened. Am I doing something wrong?

There's also a red/white wire in the connector which I believe has something to do with the thermal switch


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## thehof2012 (Jun 4, 2020)

On the fan side of things, is there anything that stops the AC from operating due to 1/2 fans not working?

I've got the VCDS-Lite and a reader to check for additional codes (hopefully early next week).. just wondering if I could get that lucky.

If I get the fan replaced, and both fans function as they should, but the AC still doesn't work, what's the next trail I should go down? The compressor gets power, I can hear the clutch kick in when AC is on, and the clutch disengages when econ is on, just like it should. The AC system does have refrigerant and is sealed up.

Any troubleshooting is appreciated here. I'm thinking IF the AC still doesn't work after fan replacement, then the pressure switch would be the next route? Hoggy, I've seen you post a few times and have pictures of the location (behind the motor, under the cross bar). Seems like a pretty straight forward swap out.

Is there another pressure switch up by the condenser? Does anyone know if VCDS-Lite is capable of giving me codes that could help me pinpoint this issue?

As always, much appreciated!


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## Hoggy (May 8, 2002)

Hi, The High pressure switch before 2001 F129, can be tested by jumping the terminals. 
Jumping terminals 3&4 should run both fans. 1&2 should engage compressor clutch 
The later G65 can't be tested that way.
Hoggy.


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## classexa (Jun 7, 2020)

So the fan motors work and I jumped the wires in the thermo switch. The fans works both at low speed and high speed. So if I've low/no AC gas, could this be the cause of the fans not spinning? It's either that or a faulty thermo switch. But shouldn't I get a code on the switch if it was faulty? I'm leaning towards the low gas part


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## Hoggy (May 8, 2002)

classexa said:


> So the fan motors work and I jumped the wires in the thermo switch. The fans works both at low speed and high speed. So if I've low/no AC gas, could this be the cause of the fans not spinning? It's either that or a faulty thermo switch. But shouldn't I get a code on the switch if it was faulty? I'm leaning towards the low gas part


Hi, As I said faulty thermal switch won't prevent them running for the A/Con, but low gas press amongst other things will.
Hoggy.


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## classexa (Jun 7, 2020)

Aa thank you. I think we might have the culprit here. I'm filling it up with gas tomrrow. I'll report back. I'm very grateful for your help [smiley=book2.gif]


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## classexa (Jun 7, 2020)

It was very little gas left but that wasn't the problem. It cooled for like 5min and then stopped. I'm gonna replace the compressor
'


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## Hoggy (May 8, 2002)

classexa said:


> It was very little gas left but that wasn't the problem. It cooled for like 5min and then stopped. I'm gonna replace the compressor
> '


Hi, Did both fans run while it was blowing cool?
Hoggy.


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## classexa (Jun 7, 2020)

Oh man, I forgot to check. I was just excited to have cold air again [smiley=bomb.gif]


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## thehof2012 (Jun 4, 2020)

Hoggy said:


> Hi, The High pressure switch before 2001 F129, can be tested by jumping the terminals.
> Jumping terminals 3&4 should run both fans. 1&2 should engage compressor clutch
> The later G65 can't be tested that way.
> Hoggy.


Hoggy! Just felt obligated to send some follow up on my work over the weekend. I was able to:
1) rip out the old "large" radiator cooling fan. 
2) had to drain coolant to get the "old fan" out, but moreso to get the "new" fan in (just a tad longer on the motor). 
3) Got the new fan in, filled with coolant, and my TT gets up to temp, thermostat opens, gets right up to 98-99C, fans both kick on like a dream!
4) I've got both fans kicking on as they should (when they're up to temp, or when I'm running the AC)

SO, the fan / coolant / ECT sensor is all happily behind me. I got the VAG Cable and VCDS Lite downloaded, but I'm having issues with the driver for the cable (go figure). It came with an install CD, but I only have a laptop w/o Disc Drive... so I'm not sure what to do here. I may have to buy a USB Disc Drive just to get the driver installed, before I can get VCDS-Lite readings.

Which begs the question.... Does VCDS-Lite give HVAC Troubleshooting / Code Reading? Or, do I need the full/complete version?

At this point (holding my breathe) the ONLY thing wrong with the car is I can't get the AC to kick on... has voltage, compressor/clutch kick in as normal, but the Low Port is reading very high pressure.. any thoughts? Could this be a bad pressure switch/sensor? I tore off the strut brace last weekend and had a look at the G65 Sensor... I have no idea how I'll get a wrench in there to loosen that! Any ideas?

As always, I appreciate the feedback and support!


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## PlasticMac (Apr 25, 2017)

You can download the driver from lots of sites, including Micro Soft. Look for CH340 drivers.
Mac.


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## thehof2012 (Jun 4, 2020)

Thank you Mac! I'll give that a shot.

Appreciate it!


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## PlasticMac (Apr 25, 2017)

Forget the CD. Only use the official version, from Rosstech. Install it, then install the driver. Switch off. Plug the lead in, switch on, and with luck, it'll pick up the driver. If you plug the lead in earlier, it'll pick up a generic USB driver, which is not the USB to serial driver you need. You'll then have to uninstall the device, and install the right driver, switch off, plug lead in, and switch on. 
Good luck. 
Mac.


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## thehof2012 (Jun 4, 2020)

PlasticMac said:


> Forget the CD. Only use the official version, from Rosstech. Install it, then install the driver.


So I did install VCDS-Lite from Rosstech's website. You're saying to only use the "full" version, and not the Lite? I'm really only hoping to use it to pinpoint the AC issues I've been seeing.. Does anyone know if VCDS Lite reads HVAC codes?

When I said "CD", I meant the install CD for the driver I got from eBay. I was hoping to install it on another laptop (work 'top), but admin rights won't allow sadly.

So, I have the official VCDS-Lite downloaded, a cable to hook up, but I need the install for the driver since my laptop doesn't have a disc drive. I'll try the driver you mentioned above, hopefully it works!

At this point I don't want to purchase the full version of VCDS until I know for sure the Lite will work... and honestly I fear I'll end up forking over a pile of $$$ to fix the AC with or without VCDS.

Thoughts? Appreciate 'em.


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## PlasticMac (Apr 25, 2017)

Download vcds-lite from Rosstech and the driver from MS (safest).
Install both from the download. Switch off. Plug in cable. Switch on. Nothing external, other than the ebay cable.
Mac.


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## classexa (Jun 7, 2020)

A small update: Replaced my thermostat since it only reached 70 degrees. Now the fans work and it reaches operating temp. But replacing a thermostat should have nothing to do with the fans right? So maybe it was the gas? But they didn't work after I filled it with gas. So I don't know


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## PlasticMac (Apr 25, 2017)

Did you get anywhere with vcds? It would help if you could scan it.
Mac.


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## classexa (Jun 7, 2020)

This was the first scan I did after I bought the car:



> Monday,08,June,2020,13:26:01:02198
> VCDS -- Windows Based VAG/VAS Emulator Running on Windows 7 x64
> VCDS Version: 20.4.0.1 (x64) HEX-V2 CB: 0.4508.4
> Data version: 20200331 DS317.0
> ...


This after I cleared it:



> Monday,08,June,2020,13:30:31:02198
> VCDS -- Windows Based VAG/VAS Emulator Running on Windows 7 x64
> VCDS Version: 20.4.0.1 (x64) HEX-V2 CB: 0.4508.4
> Data version: 20200331 DS317.0
> ...


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## PlasticMac (Apr 25, 2017)

Sorry, I expected a clue at least!
But, an (almost) error free scan is good. 
Mac.


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## thehof2012 (Jun 4, 2020)

Hey guys! Here I am again!

Over this week the previous owner sent me the list that the prev. prev owner (I know...) who was a mechanic had done to the car.

There's a nice list of upgrades/updates that have been done, and it's making me feel better about the car in general.

I noticed that on his list, he stated "new AC Control Head (Broken switch)" ... I'm wondering if that's enough detail to know the switch he's referring to is the G65 Sensor, or not? When I replaced the sensor (last night) the old sensor has the Audi logo on the bottom so I'm sure it's genuine.. but I can't tell if it's a replacement or the original..

Anyways, I replaced the G65 Sensor last night, still no AC. Compressor still functioning like it should. I STILL have not gotten VCDS Lite to work on my crappy Windows 8.1 laptop (ancient). I'm factory resetting it now and reinstalling everything in hopes that I have better luck.

This all begs the question -- Does anyone know if there's a code that "could" be present, that just needs to be reset? Or, am I getting to the point of knowing that something major is wrong with the AC? Again, no leaks, holds pressure, compressor operates... I'm getting lost.

Any help is appreciated!


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## PlasticMac (Apr 25, 2017)

Do you know if the evaporator is getting cold? If it is, then the problem could well be air flow/flap related. The AC could be OK, and the evaporator could be cold, but if the heater flap is wide open, no cold air can flow.
Mac.


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## classexa (Jun 7, 2020)

So yesterday on my way home from work it started to blow cold air for like 5 minutes and then stopped. Is this a compressor fault?


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## PlasticMac (Apr 25, 2017)

classexa said:


> So yesterday on my way home from work it started to blow cold air for like 5 minutes and then stopped. Is this a compressor fault?


Only a guess, but my money is on a temperature flap related fault, not the compressor.
Mac.


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## classexa (Jun 7, 2020)

What about this fault code:

00604 - Potentiometer Positioning Motor for Air Flow Flap (G113) 
30-10 - Open or Short to Plus - Intermittent

Which I had when I bought the car. What is this motor for?


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## PlasticMac (Apr 25, 2017)

Air flow flap is stuck or not moving correctly, as requested by the climate controller. Matches the symptom you have. Worth exercising them by running a test on the HVAC Controller. I think you need registered version of VCDS/VCDS Lite to do this. Big job to replace, dash out, I think. Someone will have done it, I'd guess, and give you more details.
Mac.


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## classexa (Jun 7, 2020)

Sounds like a PITA. But I'm gonna give it a try


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## classexa (Jun 7, 2020)

If the pipe is not getting cold that goes to the firewall, then the flap motor shouldn't be the problem no?


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## PlasticMac (Apr 25, 2017)

classexa said:


> If the pipe is not getting cold that goes to the firewall, then the flap motor shouldn't be the problem no?


Yes, but it did blow cold, for a while, a day or so back. VCDS points to the a flap motor too. 
Mac.


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## classexa (Jun 7, 2020)

Yes, the motor is most likely faulty and I'll try and replace it. But I don't see how that is the cause of my A/C issues. If I'm not mistaken that air flow flap controls the flow of outside air into the cabin (ie: recirculate button). I think it's V158 that controls the mix of air through the heater core/AC coils and the direction of the flow (up/down/middle vents)

But it is strange that many people have the same symptoms with the same code

EDIT: And just as I typed this the A/C started working again and the low pressure pipe was cold and nice. I don't get it


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## PlasticMac (Apr 25, 2017)

The air that flows into the cabin is a mix of hot and cold air. The ratio of hot to cold air is controlled by the flaps, which vary the ratio to achieve the desired in car temperature. The most likely failure is for the flap motor to stick in the max hot, min cold position, so you'll get only hot air (no pun intended). Cold air flow is blocked, so no air will flow through the evaporator. As others have said, if the refrigerant pipes are cold, where they go through the bulk head, the AC is OK. If not, then AC us suspect. The VCDS code you mention points to the flaps motor as the prime suspect.
The fact that many of our cars have run very little, if at all, recently, so flaps have not moved much, may have contributed to motor failure, or fluff build up drying up and solidifying, leading to the flaps sticking. 
Mac.


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## classexa (Jun 7, 2020)

Aa ok thanks, but why does the low pressure pipe only get cold every once in a while(when the A/C works) and what does this air flow flap has to do with it? Sorry for all the questions but I'm just trying to understand how the system works.


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## PlasticMac (Apr 25, 2017)

If the flap prevents air flow through the evaporator (the "radiator" through which the refrigerant flows) then the evaporator will be very cold. The refrigerant control system, the expansion valve, will reduce refrigerant flow. With little or no flow through the evaporator, the low pressure (return) path will not get cold. Only when the evaporator "warms up" a bit, will the flow increase. But, not for long, stopping again, as soon as the evaporator temperature drops, due to no air flow through it.
Without this control mechanism, the evaporator would freeze up.
Mac.


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## classexa (Jun 7, 2020)

Gotcha. Thank you for explaining. I find it very interesting. I'm gonna go out and check to see if the air flap moves at all. I'm curious lol


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## classexa (Jun 7, 2020)

Yep, that flap doesn't move at all when I press the recirculate button. This is the default mode it's in. Seems like it's closed/almost closed/in some inbetween state. It doesn't blow hot air. I get "coolish" air but not cold










So I guess the few times it moves, the A/C works? That's why the code is intermittent. But in this state, it uses recirculated air from the cabin no? I guess that air is not cold?


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## PlasticMac (Apr 25, 2017)

There are four separate flap/servos in there. Temperature, recirculate, footwell and dash (I think).
Wouldn't think recirculate would affect temperature, buy who knows, it's an Audi.
If possible, run an HVAC Controller test on VCDS.
As Silkman says elsewhere, the foam seats these flaps close onto are getting close to 20 years old, so a long period of inactivity may well mean they stick.
Mac.


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## classexa (Jun 7, 2020)

Aa ok, I thought this was the flap you were talking about. Hmm, this is not gonna be easy [smiley=book2.gif] I just find it weird that many who has these symptoms also has this code. But clearly this flap shouldn't affect the A/C


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## PlasticMac (Apr 25, 2017)

Follow this link to the "Knowledge Base:
https://www.ttforum.co.uk/forum/viewtop ... 6&t=172190
Then see Self Study Air Conditioning, near the top of that page. Read, mark, learn, and inwardly digest!
I'll be asking questions later ...
Mac.


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## classexa (Jun 7, 2020)

Yes sir!  I watched many youtube videos last night trying to learn about all the A/C components and how they work [smiley=book2.gif] :lol:


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## imartyn (Aug 31, 2015)

PlasticMac said:


> Follow this link to the "Knowledge Base:
> https://www.ttforum.co.uk/forum/viewtop ... 6&t=172190
> Then see Self Study Air Conditioning, near the top of that page. Read, mark, learn, and inwardly digest!
> I'll be asking questions later ...
> Mac.


Excellent link, thankyou Mac


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## classexa (Jun 7, 2020)

Can the compressor still be at fault here?


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## PlasticMac (Apr 25, 2017)

My feeling is that since it has blown cold now and then, the compressor is OK. Get a local AC specialist to check the pressures out to be sure. Worth a few pennies for a definitive answer.
Mac.


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## classexa (Jun 7, 2020)

Yeah I guess that would be best. It blew cold again today for a short while

What about the expansion valve? Or does that one give a code?


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## PlasticMac (Apr 25, 2017)

I think the expansion valve is just mechanical, so error codes would be for the result of it's failure, rather than the valve itself.
Mac.


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## classexa (Jun 7, 2020)

Gotcha. Leaving the car at a friend's garage, who is a mechanic, tomrrow- Plan on picking it up sometime this weekend. Let's see what happens

Really need to replace that air flap motor though. I get no fresh air inside the car at the moment. It gets very humid and gross. And when the windows fog up, the recirculated air is of no use. Can't get rid of it


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## PlasticMac (Apr 25, 2017)

Sounds like you may have more than one non functioning flap. There are four. The servo motors are quite expensive. Do an HVAC Controller check with VCDS, before writing a (virtual) cheque.
Mac.


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## classexa (Jun 7, 2020)

I know the one for fresh air is not working(V71), so I' ordered a new one which I got today. I did do a HVAC test and the only other thing I noticed was there is no air coming out of the right dash vent. What could be the cause there? Is it the vent itself?


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## PlasticMac (Apr 25, 2017)

It sounds like there's a problem in the HVAC "box" Maybe it'll be clearer once it's accessible, which it will be, for the recirc servo change.
You've had symptoms of the temperature flap, the recirculation flap and now, perhaps, the dash flap.
It would be great if your mechanic could take some photos of the HVAC mechanisms. 
Mac.
Ask him to check the linkage between each servo and it's flap.
If the servo is moving correctly there will be no errors, even if the associated flap is not.


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## thehof2012 (Jun 4, 2020)

I ended up taking my TT to a shop that would remove refrigerant and then replace it. In the process they told me the worst, my compressor is toast. I don't hear any loud noises or anything like that, the clutch engages/disengages, but it's "always on" and not building/sending pressure through the system. I was ~2.5oz "low" from what they measured, there's dye in the system now to see if there are any leaks.

SO, now comes the decision to replace the compressor myself, or pay to have it done. (They quoted me $900!!!!)

I've seen some how-to's and different forum posts on replacing the compressor, curious on people's thoughts -- good or not so good idea?

I can purchase a refurbished (<$100) or new compressor for less than $200.. it's gotten my interest! Based on no noise, I'm hoping that nothing is dislodged in the system, condenser / evaporator work, ect..

Thoughts!?


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## classexa (Jun 7, 2020)

If there's no gas in the system then I would replace it myself


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## thehof2012 (Jun 4, 2020)

Unfortunately for me, the shop decided themselves to put refrigerant back in, so it's back in the system.

Again, no leaks, so it'll still be in there. I will have to work out with that/another shop on getting it emptied out first off.

I've tried searching across various forums but I can't find any definitive "instruction" or how to on this compressor replacement.

As the compressor failed, I'm reading that I should replace the accumulator/drier, but should the condenser also be replaced?

If so, I'm assuming the easiest method would be to remove the front bumper, remove the alternator, and be able to get to the compressor and condenser from there? Can anyone confirm (car's still at the shop) the accumulator/drier is attached/mounted to the condenser, correct?

I never heard any noises, whines, ect, I have no idea if there's crud in the AC system or not from the bad compressor.

Just looking for tips, point me to a forum if you're aware of one, I'm trying!

Thank you


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## outdoor stevie (Nov 24, 2013)

Simplist job is to replace the compressor only, two types are available, shine a torch down onto yours and you should see a coloured sticker on the compressor it should be green or blue replace like with like. Access is required from above and below no need to remove the bumper or the alternator, remove the charge pipe, take the tension off the belt after first marking on it the direction of travel, it's held in with two long long bolts which you will need some deep sockets to reach one of them, on the back of the compressor are two gas lines held on with Allan keys undo them do not twist these as they have a wee locating lug on them to keep them aligned, and a couple of electrical connections and that's it easily doable if you are handy! Probably need to lever out the unit as it will have been in for years and you may need to grind down or file of the mounting lugs inside face in order to fit in the replacement so get stuck in lad and give it a go I'm sure you will manage it.

Stevie


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## thehof2012 (Jun 4, 2020)

outdoor stevie, I really appreciate your feedback!

I'm really, REALLY tempted to just replace the compressor and give it a go, I'm just teriffied of having the same problem down the road is my only thought.

I can get a refurb'd compressor for like $100 USD, and I then wouldn't have to remove the bumper which would save a lot of time. I know it's the "quick route", but it sure would be nice if it worked!

I'll have to look on the bottom of the car to see if/what is in the way there. I'm hoping to drive the car up on ramps, and have enough access to top/bottom as needed. Not removing the alternator would be very nice, too! Assuming with the alternator in, the compressor would have to be removed from the bottom of the car?

Appreciate the tips!


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## outdoor stevie (Nov 24, 2013)

The right hand side wheel needs to come off and the plastic wheel well trim that keeps the crud off the engine needs to be removed to gain access to the long bolts from inside the well area, the plastic under tray also needs removing to get yer hands to the back of the comp to manoeuvre it about.

Stevie


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## thehof2012 (Jun 4, 2020)

Sounds simple enough!

I've got a shop that'll suck the R134A out the day before, I can swap the compressor, and bring it back to get refilled.

I think that's the route I'll try and go here.. hopefully it works out! Appreciate the help, I'll be back if there are questions/issues, and/or hopefully a good resolution at the end of all of this!


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## PlasticMac (Apr 25, 2017)

Don't forget oil for the compressor. New ones come ready filled I believe. Not sure about recons though.
Mac.


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## thehof2012 (Jun 4, 2020)

That is a great point. I asked the same at one I'm looking at (remanned) on eBay. Saw on a forum that it's supposed to have 5oz of PAG 46 -- is that correct?


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## PlasticMac (Apr 25, 2017)

I'm not an expert, so I'd suggest that once you've identified which type of compressor you have, look at the spec for the answer.
Mac.


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## classexa (Jun 7, 2020)

My friend just replaced my compressor and the A/C now works. Said it was something about the clutch that was not up to par. Yay  Didn't have time to do the flap motor this time


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## thehof2012 (Jun 4, 2020)

I've got a used compressor coming to me by July 3 from eBay. I spent a whopping $47 on it. (free shipping, too!)

I figure I can try the cheap route and just replace the compressor with a used OEM one. If something is still in the system, the used compressor may go out, and if it does I'd replace the condenser, drier/accumulator, and the compressor all with new at that time.

For now, wouldn't it be nice if a used one went in and it all worked for the next 5-10yrs!? Wish me luck, I'll let you know how I turn out!


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## classexa (Jun 7, 2020)

Good luck. Hope it works!! I got myself a new compressor for $100.


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## classexa (Jun 7, 2020)

A question. Since the flap motor is already dead it seems, can I move that flap manually so it let fresh air in? Just temporary until it's replaced


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## PlasticMac (Apr 25, 2017)

If you can get to it, yes. Unplug the connector, in case it shuts again! Do check the foam seat, in might just be stuck. You might be lucky. 
Mac.


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## thehof2012 (Jun 4, 2020)

outdoor stevie said:


> Access is required from above and below no need to remove the bumper or the alternator, remove the charge pipe, take the tension off the belt after first marking on it the direction of travel, it's held in with two long long bolts which you will need some deep sockets to reach one of them, on the back of the compressor are two gas lines held on with Allan keys undo them do not twist these as they have a wee locating lug on them to keep them aligned, and a couple of electrical connections and that's it easily doable if you are handy!


Ok so dumb question. I've got the TT jacked up, tire off, inner guard back, and I'm trying to determine what needs to come out to get at the compressor.

Is the charge pipe the long pipe running between the intercoolers? Do I need to remove an intercooler? Still unsure how this thing is supposed to come out.... It's come out the bottom/wheel well, correct? Help! Trying to accomplish this, this weekend.


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## thehof2012 (Jun 4, 2020)

So yes, I was able to get the boost pipe off, and I also removed the vaccuum/hose electric plug in down there, too.

Sorry for the bad descriptions!

So at this point I'm on to releasing the belt tension.

Still confused on how this compressor will come out of the car. We'll see!

I did have to forcefully pull to get the driver wheel inner cover to come loose. It had these two crappy nut less lock washers and no bolt head. Assuming this is relatively easy to replace with new? The bolt looked to be welded to the frame, so I'll just need a couple nuts and should be good there.

Any more description on the actual removal of the compressor?


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## classexa (Jun 7, 2020)

I think you'll have to remove the powersteering pump from the bracket to get to the compressor


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## thehof2012 (Jun 4, 2020)

Power steering pump.. that's not pressurized, right?

Put a bucket under it, unmount, remount afterwards and fill the resovoir up top? I'll do some searching


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## classexa (Jun 7, 2020)

I don't know if you actually have to remove any hoses. Think you can just swing it outta the way somehow


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## classexa (Jun 7, 2020)

This is what ElsaWin says:










Removing PS pump from bracket:


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## thehof2012 (Jun 4, 2020)

Helpful! Thank you! I will get the pulley off the power steering pump, and get at those bolts that mount it into the bracket. From there, sounds like it should be pretty simple.

I've already gotten the system vacd out, is it easier to remove the HP and LP ports on the back of the compressor before removing the compressor?

Excited to get this AC running! It feels over 100f outside whilst I putter underneath my TT.


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## classexa (Jun 7, 2020)

If they're accessable then I would remove them while the compressor is still in the bracket


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## outdoor stevie (Nov 24, 2013)

No need to remove the power steering pump unless you want more space to work! Undo the fluid lines from the back but do not twist them whilst they are attached otherwise you may break the wee lugs in them! Undo the electrical connectors, undo the compressor mounting bolts deep socket reqd. The charge pipe (big silver pipe on top) needs to be undone to gain access to the wee lug that moves forward when you put a spanner on it to take the tension off the belt, the lug lever has a hole in it which you can put a spike or a big nail thro to keep the tension off, if you have Spring washers holding your plastic bits on then they screw off by placing a flat bladed driver in the slots and undoing them!
Good luck you are almost there!

Stevie


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## thehof2012 (Jun 4, 2020)

Anybody know the capacity of the power steering pump/system? Oops..

Gotta get that filled back up before I can even start the car! It's all sealed back up, Monday or Tuesday the AC system will get vacd out and filled (need to fill power steering back up first though!)

I've found CHF 11S online for the power steering -- correct? Do I need a liter? I checked the dipstick and it's waaaay to the bottom of it, maybe a cm left in it.

It's getting there!


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## thehof2012 (Jun 4, 2020)

Worth noting. I ended up draining the PS Pump, but didn't remove it, just pushed it down a bit.

So I get the old compressor out, 1.5oz of PAG46 in the new compressor, mounted and installed.

Started putting the PS pump back on, and it slipped out entirely. When it slipped, I noticed a spacer fell out that must have been wedged between it and the bracket..

Did some searching, I think this spacer is from the compressor.. it must have fell out when I removed the original and I didn't notice whatsoever!

So... The new compressor is already installed, everything is nice and tight, it all lines up with the rest of the system. Nothing moves, nothing. What is the purpose of this spacer? Is it a huge HUGE deal to attempt operating this system without it? I just didn't feel like it was needed. It's in the garage now, I'll try to get a picture tomorrow

I don't want to sound lazy... But 5hrs under this thing and finding a stupid spacer after everything!? Bah.


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## LVS (Feb 25, 2020)

I think there are optional spacers between the magnetic clutch and the compressor to get the spacing right between the two.


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## thehof2012 (Jun 4, 2020)

This is a much larger spacer, seemingly to go between one of the long bolts that mount the compressor to the bracket.

I'll get a picture on here soon.. again... The thing is solid, not moving at all


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## outdoor stevie (Nov 24, 2013)

Don't fill the power steering too full otherwise you will have to remove it ! There is a set procedure To checking the level by screwing the cap down and then turning the steering wheel from lock to lock to remove the air from the system. Great job and hope it's as good as new with nice cold air for you.

Stevie


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## thehof2012 (Jun 4, 2020)

Here's pictures of that spacer.. it's possible it's totally unrelated to the compressor. Maybe it fell down there long ago and got bridged in there? Doubtful.. I know..

So, can anyone tell me where this goes, and more importantly, what it does? Lighter in the pics for size.


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## thehof2012 (Jun 4, 2020)

outdoor stevie said:


> Don't fill the power steering too full otherwise you will have to remove it ! There is a set procedure To checking the level by screwing the cap down and then turning the steering wheel from lock to lock to remove the air from the system.
> Stevie


Stevie, I appreciate it! I'll be sure to move the wheel around once I get to the "min" value, or less, to make sure I don't overfill it. I understand the levels vary pending cold/hot operation, too, which makes sense. I'll take my time, this is the EASY part now, right!?!

That last post regarding that pesky spacer is really my only concern.. and I don't know/think I'm that concerned...


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