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Matt, Engineer - BEng Hons
Category: Porsche
Satisfied Customers: 21707
Experience:  Mechanical Engineer with 20 years experience in the auto industry, 8 yrs in formula 1 engine testing
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My AC is not blowing cool air. However, my heater blows warm

Customer Question

HI - My AC is not blowing cool air. However, my heater blows warm to hot air fairly well. What is the typical reasons an '05 Cayenne AC would fail? I like the best case scenario and the worst case scenario - I want to get it repaired but don't want to spend more than 3-400 if possible. Any assistance you can provide would be very appreciated. I want you to know I took to a "german auto mechanic" that said when putting in Freon the system should take .72 and it would only take .40 he didn't put a lot of time into figuring it out but not sure if his coworker mechanic actually did any deep checking into it. So with that give me your assessment - keep in mind he may have not been completely truthful because they were busy and main focus that day was changing my trans oil . Thank you
JA: When was your last oil change?
Customer: A few weeks ago
JA: Are you fixing your Cayenne yourself? What have you tried so far?
Customer: Can you read the question about the ac I've already told you
JA: Anything else you want the mechanic to know before I connect you?
Customer: I've had an oil change and a transmission oil change and now would like to have the ac repaired
Submitted: 11 months ago.
Category: Porsche
Expert:  Matt replied 11 months ago.


1st thing to check is that the AC rad / condenser is clear of any debris and there's nothing in front of the air flow to it, next ensure that the AC pump drive belt isn't slipping and if any doubt replace it.

Also check that if there's a pollen filter to the cabin air inlet that this is clean and free flowing

Next you can test components simply by checking the temperatures by touching them with the system running. with the engine at operating temperature and the AC turned on it should be as follows:

A hot compressor / pump

A hot high pressure refrigerant line from the compressor to the condenser

A hot condenser on the inlet

A warm condenser on the outlet

A warm liquid line from the condenser to the evaporator (before the expansion valve or orifice tube)

A cold evaporator outlet line

A cold low pressure refrigerant line to the compressor

If you get a different result from the above then suspect a blockage in the line or the component whose temperature is abnormal, this can be confirmed with a pressure test

Then if you're happy the temperature control is OK ( does it do hot as well as cold?) I'd take the car to an garage that can read the pressure levels of the system so the level of gas can be checked hopefully all it needs is a re-gas ( again)

Expert:  Matt replied 10 months ago.


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