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AC Problems with 04 Passat GLX

4.3K views 5 replies 4 participants last post by  V6er  
#1 · (Edited)
I have a 2004 Passat GLX with climatronic.

The past few days I have had some problems with the AC. This morning I had no problems with the AC. On my way home this afternoon the temperature outside was about 100F, the AC worked fine when I started the car, it got cold quick. While waiting at the traffic lights with the AC on it started blowing warm air and the sound from the air vents changed, when I started driving again the AC got cold again. It did this each time I stopped at a light.

I had the AC on medium fan and LOW temperature.

I have done lots of searching on this forum and it appears there could be a number of things that could be causing this. I Got the following error codes from climatronic:
25b
318

What do these codes mean? What other things do I need to check to figure out the cause of the problem?

I recently got an oil change and inspection- no issues were reported in the inspection and this problem occurred within 2 days of having that done. Could they have knocked/ touched/ moved anything in particular during the inspection/ oil change that is causing this AC problem?

Please help!
 
#2 · (Edited)
00603 - Footwell / Defroster Flap Motor (V85): Faulty

Sporadic problems reported from the airflow control flap motors are common. I have three separate flap motor DTCs on my car right now and everything works fine. They can be ignored if they're doing their job.

00792 - A/C Pressure Switch (F129)

This one is your actual problem. Something is reading out of tolerance for refrigerant pressure, either low or high. Given that you have the problem when standing and not when driving, $5 says your electric aux cooling fan behind the A/C condenser isn't working. The system can't shed heat while standing, pressure gets too high and the compressor shuts off. When you start driving, you have natural airflow over the condenser, things cool down, pressures drop and the compressor is willing to start up again.

There's another thread over here where I posted a list of compressor shut-off codes. Check to see if it's a refrigerant overpressure.
 
#3 ·
00792 - A/C Pressure Switch (F129)

This one is your actual problem. Something is reading out of tolerance for refrigerant pressure, either low or high. Given that you have the problem when standing and not when driving, $5 says your electric aux cooling fan behind the A/C condenser isn't working. The system can't shed heat while standing, pressure gets too high and the compressor shuts off. When you start driving, you have natural airflow over the condenser, things cool down, pressures drop and the compressor is willing to start up again.

There's another thread over here where I posted a list of compressor shut-off codes. Check to see if it's a refrigerant overpressure.
That was my first thought.
Check that the fan is running correctly.
It has 2 speeds, at 100 deg F it should be running balls out.
 
#4 ·
Thanks for the replys.

jyoung8607- I read the thread you linked to. Do I have to wait until the AC has a problems again to get the code from the climatronic system? Or can I do it anytime? Also I haven't seen the climatronic flash on startup yet and the temperature appears to be right.

Is there anyway to physically tell if the aux cooling fan is working without putting the car on a lift or taking any parts out? If so how do I tell and where can I find it under the hood?
 
#5 ·
Is there anyway to physically tell if the aux cooling fan is working without putting the car on a lift or taking any parts out? If so how do I tell and where can I find it under the hood?
Turn the A/C on and look at the fan; if it is spinning but hard to hear then it is on low, if it is spinning and you can hear it over the engine then it is on high.

The pressure switch also controls the fan high speed in a sense, when the pressure is too low it will not switch to high speed.


Change you're pressure switch; easy to do once you get the refrigerant drained by a shop and remove the front bumper skin-it is on the right side by the horns.