A/C question on my 986S

My A/C is doing something strange, when I take off from a stop the volume of air remains unchanged but the cold air gets warm. If I reduce the air flow it feels cold again. I thought it was low on Freon so I took it in today but they didn't find any leaks and the system is full. Any ideas? Thanks, Carlos

... cuts out the compressor any time you press the accelerator hard.
That's so you won't loose out in a drag race, even when it's hot outside
After you've been running the A/C for a while the evaporator is cool and takes a minute or so to warm up with outside air so you don't feel the difference, but when you've just turned on the A/C and the evaporator is HOT, the outside air comes through uncooled and you feel the difference.

Happy Boxatering,
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

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Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

Thanks Pedro, That makes sense, but it's blowing warm just from stopping for a traffic signal or while I'm driving along. Is that normal, I don't remember it doing that before.

Quote
Naples986
Thanks Pedro, That makes sense, but it's blowing warm just from stopping for a traffic signal or while I'm driving along. Is that normal, I don't remember it doing that before.

The most common cause for that behavior is the system is low on refrigerant. You say you had the system checked.and no leaks were found and the system full. I hate to bring this up, but how long did this take? A full A/C system checkout takes some time. When one takes a car in for something like this and 15 to 30 minutes later the word comes back "everything's ok" I have to wonder just how thorough the system check out,

To really check out the A/C the system is evacuated using a vacuum system. All the refrigerant is removed along with possibly some compressor oil. The system is kept under a very low pressure, a vacuum, for used to be just 30 minutes but this has been increased to IIRC an hour now. If the low pressure holds the system is refilled with the proper amount of refrigerant and compressor oil and then tested.

If the low presusre doesn't hold or if there is sign of a leak then of course the leak is fixed and the system evacuated again and retested.

There are some things you can do. Be sure both radiator fans come on when the engine coolant gets hot enough. With A/C off dirve the car around town until the engine is fully up to temperature. Back home raise RPMs to 1000 and hold. Have a helper confirm when the fans come on. Check that both are runnig and blowing the same amount of hot air out.

The fans should run untl the coolant temp drops. When both fans quit wait say 30 seconds then turn on the A/C. Confirm both fans come back on again.

If you find a problem with a fan that can explain the A/C behavior. However, I have had two occasions when a radiator fan wasn't working and the A/C worked just fine with one fan. And the engine coolant temperature was unaffected as well. Still you want to be sure both fans are working properly.

If you find the fans are ok and teh A/C behavior continues there's a probelm. It may not be from low refrigerant but some controller issue or something internal to the system. In this case you'll have to seek out a place that can id the cause of the behavior and fix the cause.

"controller issue or something internal to the system" Yep that is what the shop thinks too, thanks Marc. They are going to look at the controller and internal possibility on Monday.

You know me well . Doesn't going faster fix everything

just move to Ontario.

Between the apple fritters and Tim's it's a very tempting idea