HELP! A/c not blowing cold air

[Silberschonheit]

Hey guys,

My A4 B8 purchased in '11 which is sparingly used (done 24k kms only) suddenly stopped blowing cold air. I have read several threads discussing this problem but I have certain questions which I need to confirm...

Discussed in an earlier thread .....


"There's a hundred reasons why his a/c might not be blowing cold air. A proper diagnosis is to check the a/c electronics for faults and check if and what compressor shut off condition exists, from there can lead to say checking (for example) why the high pressure sensor reads 0 bar pressure as it could be a leak, it could be a faulty sensor, it could be a pinched wire or corroded connector at the high pressure sensor, even a bad module is possible. You could also have a faulty evap. temperature sensor reporting a false reading causing the compressor to go to 0% duty cycle. You could have a malfunction with the blend doors, the list goes on and on. You use A/C gauges, temperature probe, multimeter, etc... to determine the cause of the problem you find using the measured values read from the a/c electronics with the scan tool"


1. Will a VAG com diagnostics pin point exactly where the problem lies?

FWIW, I'm in Asia and do not have shaded parking, the car is exposed to heat and heavy seasonal rains.

Another funny problem I'm having is, all year round my speedo cluster gauge LCD screen shuts off, goes blank. But as soon as it starts to rain the screen comes alive, any guesses what could be triggering this, how can I rectify it?

Thank you in advance

[elscotto80]

A scan would be a good starting point. Mine didn't blow cold air once when i got it back from the shop, turned out they forgot to plug in one of the connections to the compressor, easy fix.

[Zach L]

Seems like the pressure switch on the compressors are a common issue for VAG vehicles. If diagnosed as a bad compressor, may want to check that before replacing the whole unit.

[Silberschonheit]

A scan would be a good starting point. Mine didn't blow cold air once when i got it back from the shop, turned out they forgot to plug in one of the connections to the compressor, easy fix.

Right, I guess a scans the way to go forward, but I'm told there are no guarantees it will pin point the problem area?

[Silberschonheit]

Seems like the pressure switch on the compressors are a common issue for VAG vehicles. If diagnosed as a bad compressor, may want to check that before replacing the whole unit.

I truly hope it's the pressure switch and nothing major like the compressor (the cars done just 24k kms) fingers crossed ;)

[Zach L]

Right, I guess a scans the way to go forward, but I'm told there are no guarantees it will pin point the problem area?

Correct, chances are a scan won't tell you the cause of the issue, but it's worth a shot nonetheless.

[Silberschonheit]

Any chance there's a thread with instructions or pictorials explaining how to change the A/C high pressure switch?

[Gunnark100]

Any chance there's a thread with instructions or pictorials explaining how to change the A/C high pressure switch?

Do this at service as they drain system before replacing sensor, if your system is not empty:
http://www.audizine.com/forum/showth...eam-everywhere

You need to fill system after anyway and they checking for leaks as well !

Scan your car first!

Use google translate for the link in my post, there some info as well!

http://www.audizine.com/forum/showth...1#post11623274

[StevieB67]

Do this at service as they drain system before replacing sensor, if your system is not empty:

Scan your car first!

Use google translate for the link in my post, there some info as well!

http://www.audizine.com/forum/showth...1#post11623274

This is not correct... the high pressure switch can be replaced without losing any R134. The sensor screws into a schrader valve. The sensor is located on the driver's side of the A/C condenser (underneath the hood latch cowling). It's about a 5 minute job.

[blbroo]

This is not correct... the high pressure switch can be replaced without losing any R134. The sensor screws into a schrader valve. The sensor is located on the driver's side of the A/C condenser (underneath the hood latch cowling). It's about a 5 minute job.

I second this. You lose a TINY bit of coolant changing this sensor. Easy part to swap out.

I have a brand new one at home, if anyone wants to buy it, FYI. Bought it, and discovered my problem was a leaking condenser

[Gunnark100]

the high pressure switch can be replaced without losing any R134.

You correct !

t The cooling output cannot be checked with the refrigerant pressure and temperature sender -G395- removed. The operating and display unit (Climatronic control unit -J255-) does not switch on the air conditioner compressor.
t The refrigerant circuit remains closed (connection with valve).


I had a bit other story, which involve leaking test as well.

[S4_SH1640]

Since on this subject....

Did anyone have to replace the A/C compressor? Do you know if the A/C compressor clutch is replaceable without changing the whole compressor? Or anyone have a DIY for replacing the A/C compressor?

The reason why i ask is because at normal idling, i am getting a noise which i think its coming from the compressor. I feel it on the steering wheel as soon as i turn on the A/C. But when i start driving, the noise goes away. A/C works fine on either idling or driving.

[blbroo]

Since on this subject....

Did anyone have to replace the A/C compressor? Do you know if the A/C compressor clutch is replaceable without changing the whole compressor? Or anyone have a DIY for replacing the A/C compressor?

The reason why i ask is because at normal idling, i am getting a noise which i think its coming from the compressor. I feel it on the steering wheel as soon as i turn on the A/C. But when i start driving, the noise goes away. A/C works fine on either idling or driving.

Check all of the pulleys through the drive belt. It might be something similar that just acts up with the AC puts more load on the belt.

[Alex1188]

Since this thread is about AC, what you auto trans guys get for engine vacuum pressure with AC on in drive?

[Party_Marty]

Does anybody have issues with air flow? I can hear my main fan whirling but it seems obstructed and the vents aren't blowing normal, anybody have any idea?

[Silberschonheit]

I second this. You lose a TINY bit of coolant changing this sensor. Easy part to swap out.

I have a brand new one at home, if anyone wants to buy it, FYI. Bought it, and discovered my problem was a leaking condenser

You've got a PM, Sir.

[Silberschonheit]

This is not correct... the high pressure switch can be replaced without losing any R134. The sensor screws into a schrader valve. The sensor is located on the driver's side of the A/C condenser (underneath the hood latch cowling). It's about a 5 minute job.

Come Monday, I'm planning to take my car to the "Stealership" and get a scan done, which I assume might pin point the problem, am I being optimistic or will the scan truly show the malfunctions?