AC problems - Need advice

B6/7 S4/RS4
#1

Hi Guys,

I am wondering if some members may have encountered the same problem as I have with my car.
Car is a 2007 B7 S4 Cabrio with 38000 km on the clock. I purchased it in January smashed (front) and it took me 3 months to rebuild it.
At the beginning AC was working flawlessly however I have now some problems with it.
To sum up, it is working on and off and it is difficult to isolate the cause. At first I thought that the compressor was dead as the AC was working for a couple of days and stopped. I was ready to order a new one but then AC started working again. Sometimes the AC needed a good acceleration to kick in, sometimes I was running normaly.
Somebody told me that it could be some humidity within the system and that I should vaccum it and recharge it again. I did that last week and put some new oil in the compressor as well. The system is still running when it decides!! >:( However when it works, the air coming out of the vents is really cold, so for now I am tempted to rule out the compressor.
Lately the weather in Montreal has been really humid and the AC never kicked in. Do you think it could be related?
Some people are suggesting to change the dryer.
Have you experimented something similar, I can use any advice.

Thx

#2

Sounds like the solenoid in the compessor is failing…

#3

Is the solenoid replaceable without replacing the compressor?

#4

I have the exact same problem. Sometimes the a/c works just fine,sometimes it just blows warm air. I have to turn the a/c off then back on several times and then it will start blowing ice cold again so I doubt it’s a low refrigerant issue.

I’m fairly certain in my case it is something electrical/electronic. If it were a case of a leak and low on refrigerant,the problem would be consistant and not random. Random problems like this tend to be electrical in nature. (I have a background in residential a/c - principals are almost the same between automotive and residential,specific componets being the difference)

I just have to figure out which relay or sensor is the problem.

#5

The Compressor units on these cars is made of glass (not literately) check vag com see if there is any codes and then it might be best to drain and recharge the unit. Discharge and check the compressor