Intermittent AC problems...
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Intermittent AC problems...
I've been having an odd problem with my A4's air conditioner.
When I start the car, I get cold air for about 30 seconds before the AC compressor cuts out, and the blowers start venting hot air into the cabin.
If I wait a few minutes, and press the "snowflake" button twice to reset the compressor, I get cold air again. Sometimes this is enough to make it stay on, sometimes not. Because I can usually eventually get it to work, I'm assuming there's no coolant leak.
This problem only manifests itself when the outside temperature is above 90 degrees.
Am I to assume that the AC Clutch Relay is the most likely culprit? How can I confirm this diagnosis, and replace the relay?
(I have a 1999.0 B5 A4 2.8 with 146k miles. I'm not particularly enthusiastic about throwing a lot of money at this problem)
When I start the car, I get cold air for about 30 seconds before the AC compressor cuts out, and the blowers start venting hot air into the cabin.
If I wait a few minutes, and press the "snowflake" button twice to reset the compressor, I get cold air again. Sometimes this is enough to make it stay on, sometimes not. Because I can usually eventually get it to work, I'm assuming there's no coolant leak.
This problem only manifests itself when the outside temperature is above 90 degrees.
Am I to assume that the AC Clutch Relay is the most likely culprit? How can I confirm this diagnosis, and replace the relay?
(I have a 1999.0 B5 A4 2.8 with 146k miles. I'm not particularly enthusiastic about throwing a lot of money at this problem)
Audiworld Junior Member
Joined: May 2010
Posts: 55
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From: NE Ohio
if you can get it to fail in your driveway probe the clutch wire with a multimeter. if its getting 12v and the inner hub of the compressor isnt turning it could be the clutch coil or the "air gap" is too wide. start there
AudiWorld Super User
Joined: May 2002
Posts: 5,138
Likes: 4
From: Redmond WA
I've been having an odd problem with my A4's air conditioner.
When I start the car, I get cold air for about 30 seconds before the AC compressor cuts out, and the blowers start venting hot air into the cabin.
If I wait a few minutes, and press the "snowflake" button twice to reset the compressor, I get cold air again. Sometimes this is enough to make it stay on, sometimes not. Because I can usually eventually get it to work, I'm assuming there's no coolant leak.
This problem only manifests itself when the outside temperature is above 90 degrees.
Am I to assume that the AC Clutch Relay is the most likely culprit? How can I confirm this diagnosis, and replace the relay?
(I have a 1999.0 B5 A4 2.8 with 146k miles. I'm not particularly enthusiastic about throwing a lot of money at this problem)
When I start the car, I get cold air for about 30 seconds before the AC compressor cuts out, and the blowers start venting hot air into the cabin.
If I wait a few minutes, and press the "snowflake" button twice to reset the compressor, I get cold air again. Sometimes this is enough to make it stay on, sometimes not. Because I can usually eventually get it to work, I'm assuming there's no coolant leak.
This problem only manifests itself when the outside temperature is above 90 degrees.
Am I to assume that the AC Clutch Relay is the most likely culprit? How can I confirm this diagnosis, and replace the relay?
(I have a 1999.0 B5 A4 2.8 with 146k miles. I'm not particularly enthusiastic about throwing a lot of money at this problem)
There's a switch in the radiator that controls the fan/ speed.
Check to make sure the airflow through the condenser isn't blocked, it's in front of the radiator so hose it down.
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AudiWorld Newcomer
Joined: Dec 2009
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Sounds like the high pressure switch is tripping. If the condenser is too hot it will trip. Are both the mechanical and the two speed electric fan running (on both high and low speeds)?
There's a switch in the radiator that controls the fan/ speed.
Check to make sure the airflow through the condenser isn't blocked, it's in front of the radiator so hose it down.
There's a switch in the radiator that controls the fan/ speed.
Check to make sure the airflow through the condenser isn't blocked, it's in front of the radiator so hose it down.
Browsing through the rest of the forum, this is evidently a somewhat difficult repair to DIY, so I may just have to tough it out for the rest of the season. Le sigh...
Audiworld Junior Member
Joined: May 2010
Posts: 55
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From: NE Ohio
well, it'll only really be a problem when you're not moving or if its really hot out and you're at idle or driving slowly. once you're moving and enough air is getting through the front of the car the pressures will come down. have you ever taken the front end of the car off? if you have its not a terrible job. there's an a6 in the yard near me with the aux fan in it if you need one. did he check all wiring/fuses to be sure the actual fan motor is bad?
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