Gentlemen:
Ambient temp 95 degrees, low side pressure is 55psi but when compressor kicks in goes up to almost 100 psi. Then I assume a high pressure switch kicks in and pressure drops. Yet driving the car there is cooling in the cabin.
Any ideas?

Thanks

 

Here is the Jaguar ambient temperature chart if that helps. The low side pressure you describe seems strange.

 

You may find this thread interesting reading https://www.jaguarforums.com/forum/s...reasure-54416/

Do you know what the high side is doing?

 

Haven't check high side yet, what I can't figure out is why the low side goes up and down.

 

It is normal when the compressor is not running for the low and high side pressures to equalize. When active the compressor draws gas from the low side and compresses it to a liquid on the high side, this process releases the heat (removed from the cabin air) via the condensor.
During this process it is normal for the high side pressure to increase considerably, enough to make the gas return to a liquid and at the same time release it's heat. At the same time this causes suction on the low side causing it to reduce in pressure. (Both pressures dependant on ambient air temperature) If this pressure falls too low, and everything else in the system is operating correctly, it would generally mean that there is insufficient liquid/gas coming through the evaporator - a lack of refrigerant.

In your case the low side pressure is going higher, and as the cabin air is being cooled this could suggest (one option), there might be too much flow coming through the expansion valve (faulty) to the evaporator and on to the low side reading.

You really need both the low and high readings to be more specific.

 

good explanation stumpy!

 

protech

Another thing that you should check is the climate control diagnostic system, to see if any codes are listed?

Instructions and code information here: