Hey all,

I can find all kinds of information on this for any other car but not my 1992 VDP.

While driving above ~30MPH the ac is nice and cool. Under that or at idle it almost instantly heats up. Sometimes luke warm other times humid hot. Once back up to highway speeds all is good again.

Took it last year to a trusted ac guy and he said everything seems ok with the refrigerant and the relays. The compressor was changed back a year or 2 ago. It is 134A not R12.

What I have found so far is 1) check the in cabin filter (I don't think this year has one) 2) engine fan not working properly (it is) 3) dirty ac condenser (will check that later today) 4) total ac system overhaul.

While I LOVE this car, spending 1500+ on it seems really a bad idea. I have seen people add electric fans on the outside of the ac condenser and all sorts of other "redneck engineering". The relay to the ac clutch is working fine and doesn't show any corrosion or wear. The strangest thing is that it works when moving over 30mph but under is when you have issues, like stop and go traffic or idle for more than a few seconds.

Thoughts?

 

Try a R124 recharge kit (assuming your A/C has been converted). Advance, Autozone etc all sell them.

 

It isn't low on refrigerant.

 

It could be, may not be. I still suggest an R134A refill kit. Get one with the guage and follow the comprehensive instructions.

 

Did your guy check for clogged (cottonwood, bugs, etc )stuff in the radiator area? I feel for you my air doesn't work and I have decided to not worry about it.

 

An XJ40 A/C overhaul is certainly within the capabilities of a DIYer with a decent toolbox and determination to succeed.

 

Listed a few below.
see here.....


https://www.jaguarforums.com/forum/x...ighlight=a%2Fc


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I am going to get the ac in a can tomorrow and see if that works. I also think I am going to get some engine de-greaser and clean out the fins even better than I did with the hose.

there are 3 "radiator" looking things under the bonnet. 1 is obviously the radiator, one would be the ac condenser, and what is the other. Looks very very small compared to the other 2 and is on the drivers side if you are looking in under the grill.

 

The small one is your engine oil cooler. Two hoses should be attached to it.
The AC condenser is mounted to the front of the radiator.

 

Hi Rutty,

I also suspect that a blocked condenser could be contributing to your problem. It would be worth removing the fasteners on the radiator top mount plate (and possibly the electric fans and shroud as well) so you can tilt the radiator toward the engine and use a shop vac to carefully clean any leaves, seeds, rust or other debris you find between the condenser and radiator. I don't think you need to disconnect and remove the radiator, but the photos at the following links may help you see what is involved in removing the fan shroud and top mount:

Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page


Other possible causes of your problem that come to mind are:

One of your electric radiator fans is not working properly?
A/C compressor clutch is slipping?
Expansion valve is partially clogged or stuck? Does the outside of the valve frost up when the A/C is running?
Heater water valve stuck open, allowing hot engine coolant to circulate through the heater core even while using A/C?

Could there be a problem with one of the many sensors or switches, such as the Evaporator Temperature Switch, the Solar Sensor, the In-Car Temperature Sensor, the Ambient Temperature Sensor, etc.? Do you have the Electrical Guide for your model year? I have '88, '89 and '93/'94 but not '92. I don't recall what significant differences there are between '92 and '93, but if you want to see the '93/'94 manual send me your email address via private message with XJ40 Electrical Guide in the subject heading and I'll email you the manual.

Another possible contributing factor is that you may have a problem with the blend flaps in the Climate Control Unit (CCU). The photos at the links below will give you an idea of how the system works:

http://www.jag-lovers.org/snaps/snap...?id=1390920386
http://www.jag-lovers.org/snaps/snap...?id=1390867076
http://www.jag-lovers.org/snaps/snap...?id=1390836244
http://www.jag-lovers.org/snaps/snap...?id=1390831473
http://www.jag-lovers.org/snaps/snap...?id=1390775046

Cheers,

Don