A/C problem at idling
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Race Director
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From: Toronto, Canada
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A/C problem at idling
I have a problem with my car's A/C - when I am stopped at a light - it will sometimes start to blow warm air as though the compressor is shutting off.
The car runs fine otherwise and the air conditioning turns the car into a fridge when driving without stopping regardless of the outside temperature. The radiator fan comes on (even at idling) but I do notice the voltage is around 12.1 when stopped with the A/C on.
It is an 07 A6 with 55k miles. TIA
The car runs fine otherwise and the air conditioning turns the car into a fridge when driving without stopping regardless of the outside temperature. The radiator fan comes on (even at idling) but I do notice the voltage is around 12.1 when stopped with the A/C on.
It is an 07 A6 with 55k miles. TIA
Team Owner
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St. Jude Donor '15
"In honor of jpee"
I'm no refridg guy, but sometimes that happens to ac when it's low on "freon". Reason is, it's compressing when running at above idle, but loses some of that compression-ability when the rpms drop.
Today, they (meaning service places) don't just "top up" or fill a little. They almost always "drain, clean and add" which, of course, is an added cost. But it keeps the environment clean, checks for leaks, recycles used freon, and eventually "tops up" your system.
The question is to find where it can be done for the least amount, but competently. Good luck. That's my best guess.
Today, they (meaning service places) don't just "top up" or fill a little. They almost always "drain, clean and add" which, of course, is an added cost. But it keeps the environment clean, checks for leaks, recycles used freon, and eventually "tops up" your system.
The question is to find where it can be done for the least amount, but competently. Good luck. That's my best guess.
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From: San Clemente CA
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thanks for the responses - I should add that this has been going on for the last 3-4 years and I have had a new battery during this period (on a preventive basis)
Race Director
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From: Saint Albans, WV
If the situation hasn't worsened in the last several years that reduces the chance for refrigerant leak being the issue. I'd make sure the fans are running properly. Intermittent high condenser temps will cause what you describe as will a low pressure switch but as I said that doesn't seem logical.
Tech Contributor
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From: St. Louis, MO
St. Jude Donor '08
The 05's were overfilled from the factory which would cause this symptom, particularly on hot days at idle...the system would pressurize too much and kick off the compressor under high pressure. There is a TSB on it, and the fix is to remove the freon and add less. Sounds counterintuitive but it's true.
Or just let some out if you are less environmentally friendly.
You can scan the ac pressure PID if you have HP Tuners and see if perhaps your car is overfilled.
Or just let some out if you are less environmentally friendly.
You can scan the ac pressure PID if you have HP Tuners and see if perhaps your car is overfilled.
Instructor
Joined: Apr 2009
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I have had similar issues of this type on the c6 and other vehicles. You may be over or under charged. There is no real way of knowing the volume of gas inside your system, only the pressures on the high and low side. There may be an obstruction at the orifice tube, a bad compressor, or a very hot day and heat soak (although that would only be after a quick stop start like turning off the engine to refuel). The best way to begin to try to solve it is drain the system, replace the orifice tube and accumulator while your already there, then vacuum the system for 1 to 2 hours, then refill to the proper oz spec. The service manual or a search on the forum will give you capacities for freon and oil. A set of gauges and a vacuum pump can be had for about 180 these days.
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Racer
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From: Corona CA
I had the exact same problem in my 06. I bought the DIY recharge kit from Autozone because thought I was low. When I hooked up the gauge it showed I was high. It wasn't by very much. I let some out and it has been fine ever since. As was stated above, if there too much "freon" it causes too much pressure.
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I had the exact same problem in my 06. I bought the DIY recharge kit from Autozone because thought I was low. When I hooked up the gauge it showed I was high. It wasn't by very much. I let some out and it has been fine ever since. As was stated above, if there too much "freon" it causes too much pressure.
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From: Saint Albans, WV
Thread Starter
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From: Toronto, Canada
C7 of the Year - Unmodified Finalist 2021
Race Director
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From: Saint Albans, WV
Oh, that's definitely a fact. My 05 was fine for the first 6 months when new and then had the blower installed. Found that flaw immdeiately and the dealer adjusted as tsb called for. I doubt that happened after the 05 but who knows, mistakes can happen.
Burning Brakes
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Glenn
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I agree - 12.1 volts is too low, even at idle. You should see about 13.5 to 13.8 at idle - does the voltage increase above idle? If so, one of the diodes in the alternator's diode trio is probably shot. See if the AC compressor kicks in when the voltage is up in the normal range.
Glenn
Glenn
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From: Southern Utah
Burning Brakes
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From: Voorhees NJ
The 05's were overfilled from the factory which would cause this symptom, particularly on hot days at idle...the system would pressurize too much and kick off the compressor under high pressure. There is a TSB on it, and the fix is to remove the freon and add less. Sounds counterintuitive but it's true.
Or just let some out if you are less environmentally friendly.
You can scan the ac pressure PID if you have HP Tuners and see if perhaps your car is overfilled.
Or just let some out if you are less environmentally friendly.
You can scan the ac pressure PID if you have HP Tuners and see if perhaps your car is overfilled.
Totally agree..Overfill can cause the same problem and more likely at just idle...Release some and see if it continues...If not, you can always add a little more later...Didn't know it was that hot in canada during the winter???