The AC in my 2015 V6S does not blow cold at idle, but works very well while the car is moving. I have had the system tested for leaks and have also had the refrigerant levels checked and refilled, with no change in the symptoms. There are no codes that are present. The only other item that has been replaced was the humidity sensor near the rear view mirror. At times while at a stop light or similar, the compressor will kick on for a few moments and then will turn back off, only to start again once the car is moving. I have a battery gauge in the car and it seems to indicate that the (1 year old) battery is fine - 12.6 volts before it's started.

Any ideas on where to start looking? Is there an AC idle relay, or something similar? A valve/sensor that is not operating at lower rpms?

Thanks,

Matt

 

Possible bad DPS valve?
Start the car from cold. Switch on the AC. Check that the engine fan is running on slow speed.
If not then put gauges on the system and report back.

The DPS can cause strange AC pressures. If the system has too low of a high side and too high of a low side that is a strong indication of this problem.
See the attached TSB.

Now I fought this on my 2014 XJR and while the DPS valve is replaceable and can be purchased separately I now recommend just replacing the compressor as then you get a warranty and the cost is not that much more plus the DPS is already installed.
This is important for another reason as there are two different DPS valves and they do NOT interchange! The Jaguar TSB which I have attached was wrong for my VIN and I first ordered the incorrect DPS valve.

I do all my own work and got the factory Sanden compressor for around $300.

Also replace the dryer bag and consider changing the filter plug at the bottom of the dryer tube.
But first let's find out what your problem is?
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Have you checked simple things like condenser blockage and proper operation of the fan?

 

I have not checked anything other than taking it to the mechanic, describing the symptoms and getting the car back with new refrigerant. I am not qualified to locate the AC components, let alone service them. The compressor was replaced about 2 years ago for a bad valve so I suppose that could be the issues again. I am really looking for ideas so I can give the mechanic a place to start. I just need it to work long enough to sell this absolute piece of ****.

 

Thanks! I'll send this to the mechanic.

 

Take a quick peek through the grille and make sure there’s no foreign objects blocking the condenser, which looks like a radiator. Also, pop the hood and see if the fan is spinning full tilt when you have the ac engaged.

 

Lol, thanks! These are the kinds of directions I can follow. When I get home tonight I'll take a look.

 

A general rule of thumb when you have the symptoms you’re describing is not enough air moving through the condenser at idle. When you start driving, the airflow resumes and the heat transfer away from the Freon in the condenser causes the system to work again.

 

THis would be the reason behind making certain the fan is on full boogie, I would assume?

 

That’s it

 

Thanks again. I will take a look when I get home and report back.

 

When I started the car this afternoon, after having sat all day, the AC worked initially and then stopped working at stoplights per the usual. The fan seemed to be spinning fast and I can't see anything blocking the condenser.

I have a few codes, however...





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With those U codes is it possible your battery is getting old?
The problem I posted will set no codes of any kind. That's one of the problems when trying to diagnosis it. You have to go by symptoms and AC pressures.

Were you able to put AC gauges on the car?
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The battery is about a year old - it was replaced, the BMS reset, etc. I have a plug in gauge that reads 12.6 before the car is started.

I'll have to take it to the mechanic as I have no way to hook up ac gauges