Hey guys,

So my XJR has been giving me some A/C trouble.

Here's whats going on. When the outside temps are in the high 70's - mid 80's and humidity is modest to low, The car blows 42-44 degree air and can freeze you to death.

It also leaves the tell tale water trail under the car.

When The temps climb beyond that, or the humidity creeps up, it's like someone turned the A/C off. Today, 94 degrees, very hot and humid, A/C feels like a warm fan in your face. No water what so ever under the car.

We checked the compressor function and it SEEMS ok for now, High v/s low side pressure. We also vaccumed the system and filled up with fresh freon. Charge level seems correct, no leaks or loss of refigerant. There was a substantial amount of oil in the old charge.

What should I be looking at next?

Thanks in advance,

George

 

I'm seeing something of the same. My A/C seems to try and cycle between sorta cold and hot. Indicitive of a cycling compressor due to low freon. My gauges have been loaned out for a few years and I recon they liked em better than I did. Can't rememebr who I loaned em to as well. So I need a new set then I can make some determinations for myself.

As far as your system goes, trace the cold tubing and see where it stops that might tell you where the problem starts. You might have a gagged up orfice tube. I have no idea what is serviceable and what is a replacement on these cars as of yet. To be honest I would rather not find out.

Hmm you did mention that pressures looked good static and running right?Might be a malfunctioning heater mixing valve??? I have no idea just brain storming. If the pressure looks right them I would rule out the orfice thing.

 

I don't think there is a blockage.... After all, how could it be blowing cold air when its not HOT out or that humid? It's like the car is litterally night and day, at night, when its cooler, you can freeze to death. During the day, it's like someone just pulled the A/C fuses or something, like the car doesn't even have A/C.

It's not a heater mixing issue either. Been there, done that in my S-Type. It's not adding hot air to the cold air, it's just NOT getting cold, period.
But as soon as it cools off, it does.....

I'm thinking expansion valve and or reciever / drier.

Take care,

George

 

Well George, I'm certain I'll be interested in the outcome!

 

There is a humidity sensor inside the car, as well as direct sunlight and temperature sensors.

The humidity and temperature sensors are a combined unit with a little air intake grill just below and to the right of the steering wheel. Air is sucked in by a little fan past the sensors. Any blockage of this little grill will interrupt the air flow and give false signals to the CCM.

Of course it may not be this at all, but you already know the cooling circuit works, so it must be in the control circuits somewhere.

 

Fraser that's a tidbit that is worth noting!!!

 

Ok some more observations...

I think that there is some sort of blend motor failure and or other issue in the car...

I am typically a set it and forget it type of guy with the climate control. Always on auto. Between 65-70 degrees depending on the weather...

I realized this when playing around with the controls. When I first got into the car - parked all day in 95+ degree ambient temps.. Hit auto, AC on "LO" all of a sudden the car started turning the recirc on and off repeatedly.

Backed the fan down one notch (from full) and recirc would stay on. Now here are my findings. The floor and dash vents both blow air regardless of the vent selection. Dash vents, both dash and floor, or floor only selected has NO affect on what vents blow air..

Selecting the floor and defrost option does enable and or disable the defrost vents at the base of the windshield BUT the dash vents do not turn off regardless of any position.

Trying to set / adjust vents did cause some sort of higher pitched howling noise To become audible behind the dash.

The humidity dropped a bit and I started the car up again and it does cool.. NOT cold, but not the HOT air it was blowing after work...

Any thoughts would be appreciated.

Take care,

George

 

The only lights on for the CC should be the one on the 'Auto' button. Any others lit at all ? It is possible to 'latch' certain functions. This means they stay 'latched' until reset. Recirculation is one of these, there are others.

 

Some years and several Jaguars ago, a Jaguar tech advised me to cycle the AC on max cold then max hot for a few minutes each approximately once a month as preventative maintenance on valves, actuators and flaps.

I've done this ever since. Can't categorically say it's beneficial but I've avoided any more AC issues.

Graham

 

I have NAV in my car so this is on the CC screen.

Auto stays on when selected....

The rest is all on the touch screen.

Take care,

George