MikTip

<center><img src="http://pictureposter.audiworld.com/6607/coolpic.jpg"></center><p>
or thermoswitch...

MikTip

<center><img src="http://pictureposter.audiworld.com/6607/coolpic.jpg"></center><p>
"A switched output which closes a path to 0 volts when the temperature exceeds 119C. Connects to the ECU and A/C controller to reduce engine load respectively under this high temperature condition"

Has it been hot outside, where you live?

Hows your engines cooling system? Topped up with coolant?

See if you can bleed some air from your engines cooling system, as the pipe, where F76 connects into, can trap allot of air. See if any air comes out of the bleeder screw by G62?

Belle

85 degress F today.

Cooling system is topped off. No signs of boiling over due to air trapped in cooling system but I'll give bleeding it a try.

Again, the compressor works fine when F76 is disconnected.

What are your thoughts on it being an ECU problem? I just replaced the fuel pump last week. Related?

MikTip

then test components with a voltmeter, trying to determine the cause, or fault...

Are you able to get the DTC's from the engine ECU?

Belle

No vag-com. I'll test with volt meter according to instructions in Bentley, but not sure this is necessary as I replaced all sensors.

fastmk2

I know that this an extremely old post, but I have this same problem. Was there any resolution here? What solved the problem?

Thanks for the help!

CRAZY_RUSSIAN

holly poop... the dead are coming out of the graves... what have you done? and describe your problem

fastmk2

Caveat: This problem above describes the same issues I currently have, although I the engine in my Audi is not the V6 12V; I have a 1990 20V N/A engine.

Problem: AC stops working when car is fully warmed up -> Temp Needle climbs to the furthest right asterisk */* point on the instrument cluster and shuts off the AC. Auto-Check system doesn't indicate overheat mode, nothing flashing to lead me to believe there is a problem.

The thermostat was replaced in January w/ 80-C as recommended; the thermoswitch was replaced in January, too after I learned that a working thermostat didn't fix the temp gauge position on the cluster. System was flushed and bled properly, coolant is factory recommended G001100, mixed 50/50 with demin water.

Recently replaced/retrofitted system for R134A refrigerant, pulled 24" Hg on system prior to charging, jumped 12V to AC clutch to engage compressor after charging system w/ refrigerant pressure only. System is fully charged to Bentley specs and blows cold air through vents on AUTO before the car warms up, as described above.

After reading through this posting, I have disconnected the thermoswitch which allows the AC to operate as it should. I am led to believe that I have a faulty thermoswitch, thermostat (opening too late, temp slightly higher than recommended?), or the instrument cluster gauge is out of calibration.

I may try bleeding the coolant system one more time before tearing into this (easiest option IMO), but I was hoping that some additional information could be shared regarding the resolution to the original topic poster's problem.

Any advice is welcome. Thanks.

performancefz1

have you replaced the thermostat ? I have had MANY MANY problems with new and almost new thermostats . Replace it again then refill , bleed the system and as it is warming up look into the coolant res and make sure there is very little air coming up from the system ( this is a little tricky as air pockets in the system may cause a lot of bubbles ). If the coolant system is HOT in any way the ac will cut off . even if your gage is close to the norm it may still be too hot for the ac as your thermo switch will kick in and try cooling the system down . I am speak from experience >>> Audi mechanic since 1981 <<<
Another thing you can try is cooling the AC condenser with water from a garden hose , if the ac still cuts off while your cooling off the system with water then it is definitely a problem with your AC system and not the cooling system .

fastmk2

Just finished installing a brand new thermostat by Behr, 80-C... This replaced the 5-month-old Wahler 80-C thermostat.

Bled the system, reattached thermoswitch, and the gauge needle sits in the same place, the right-most dot on the instrument cluster.

And guess what - no AC until I disconnect the thermoswitch.

I'm now leaning toward a faulty thermoswitch, because as stated above, the AC works great as long as the gauge needle is below the right-most dot on temp gauge, or it is disconnected. I'm hoping that maybe someone can share with me the readings they get from the "R" and "T" pins when their car is fully warmed up, as well as a thermostat temp setting (if you know it).



Thanks for any help!