I'm having an intermittent issue with the AC. Unlike the recent post, I get a good blow.... with or without recirc, but sometimes it just blows ambient air. I've tried pressing the snowflake off for a few minutes, then back on - but no cold. Then later on, it will just come on by itself - good cold, very comfortable. Any ideas?

 

could be the clutch assembly on the AC Compressor itself. Also have you had the Freon level checked?

 

or a flaky AC relay...there are contact points in there that over time can build up carbon and not make a good connection

 

If you determine that it is the clutch assembly, don't buy just the clutch. If you go through Porsche to buy the Denso compressor they list it at $1,627.xx, and the clutch Aline for about $800, it is hard to find the clutch assembly Aline except through Porsche. Last year my AC stopped working. I ended up replacing the compressor and clutch as an assembly. I bought a Denso through RockAuto and it was less than $300 delivers, and it was the exact same Denso unit that came out of my car.

 

Haven't checked anything yet - just recently started happening. All good ideas!

 

If the engine coolant is "tending" toward overheating the A/C will be disabled.


Radiator cooling fan failure caused that effect for me.

 

As Device 2 alluded to, it could be something as simple as your AC system being right at the low end of the Freon pressure necessary for the AC system to operate.

If there is too little Freon in the system, the compressor will not kick on and you will just get hot air.

It could be possible if you are right at the threshold level, the compressor will kick on if the ambient temperature is high enough but may not if it is a bit cooler. People up here in the New England area got a great education from the Patriots regarding the ideal gas law and how temperature can influence gas pressure.

It may not be the issue, but before you start troubleshooting complex problems, try hooking an AC pressure gauge to the low pressure input of your AC system. You can pick one up at WalMart or most any auto supply store for around $20 or less.

If you are low on Freon, top the system off and see if it solves the problem. If the charge is fine, leave it alone and start looking into the more difficult fixes.

Hopefully it will be something simple and cheap to correct.

 

Good point! I've never checked it since I got the car... and who knows how long before that. It was a roller with an IMS failure that we rebuilt, so I don't have any previous owner info (except what was in the owner's manual...and a few lipsticks...).

Freon will be a good place to start!

 

You probably have a slow leak. Remember not to recharge it unless the compressor is working - otherwise, the low-pressure side is a high-pressure side and you'll blow your hand off.