So my AC was blowing cold when moving and hot when not moving. Even when on the highway it will go from ice cold to hot to cold again. I had a mechanic vacuum it out. It passed the vacuum test and they refilled it with freon. They said the low side pressure looked good, but the high side pressure was fluctuating more than it should. I got the car back and it is still doing the same thing! Is this a DCCM issue? A valve issue? A compressor issue? I will be taking it back soon and I want to avoid buying the compressor unless I absolutely have to. The car is a 2005 Jaguar S Type R. Thanks for the help!

 

Hi Rhino


Sounds like possibly the high side is your problem. Both the low side and high side will fluctuate as the compressor cycles on and off. Your low pressure should be around 20psi when the compressor is on, and the high side should be about 150-200 psi when the compressor is on. Since you say that the A/C blows cold when moving, and blows hot when sitting at idle, I would suspect the compressor. Were you able to look at the operating pressures or did the guy just tell you what the pressures were doing?

 

Try this link below. If it's not a hyper link cut and paste. It is found in the "How To" section in the S Type subdirectory.

Be sure to click and read the TSB at the beginning of thread!

https://www.jaguarforums.com/forum/s-type-15/2005-3-0-litre-ac-compressor-replaced-w-pics-faq-55212/

 

Could be a failure of your electric cooling fans on the radiator matrix. Cold on the move but hot when stopped is a classic symptom of that failure...but I'd think you'd also see some engine overheating.....

 

I have the same problem with the 4.0 V8. Cooling fan works, no hint of high coolant temperature (center of gauge at most). May not be engine specific. A friend has the same issue in a XJ6. Is this just a common weakness in the compressor itself - across multiple models and years?

 

This is very true. However, even if the cooling fan failed, he would only get ambiant temp ac air and not hot air. To get hot air, his DCCV must have failed also. Both problems are probably present.

Turn on the cabin fan and set it to ambient temperature. If you are getting hot air and not ambient temperature air, your DCCV valve is shot.

Turn on your air conditioning while not moving. If the cooling fan in the engine is not moving, your fan is shot.

 

In most cases on the S-Type, when the DCCV is faulty, with A/C on you will get cold air on one side of the dash, and hot air on the other, depending on which side of the valve has failed. Not to say it couldn't be the DCCV, but I've never seen one fail in this way. If the high side pressure is fluctuating, which it shouldn't, it sounds more in the compressor than anywhere else in my opinion. Also, when the DCCV fails, it takes out the A/C control module as well, shorting it out. If you've had the coolant resevior leak, the DCCV sits directly below the coolant resevior, and the coolant makes its way into the connector and shorts out the valve taking the control module with it. You can check from the top to rule this out, if you see coolant stains on top of the valve, its possible that's your culprit, but if not, I would be leaning towards the compressor.

 

For what it is worth before you start replacing things have the battery checked. My 2000 had the same issue no cooling at idle replaced the battery and all was good.