Doug please feel free to chime in here... I have looked through some of the older posts but still have a few questions.

The AC on my 1989 XJS has no temperature control. Air seems only slightly cooler than ambient. Adjusting the temp control makes no difference to the air temp. It does operate the vent flaps.

A list of the things I have checked so far:

* Heater control valve - No movement when adjusting the temp control. I assume this should be free enough to close by hand, mine might be seized..

* Auxiliary fan not operating - can not find anywhere in the ROM where it describes the AC function of the fan, except that it should operate.

* AC compressor clutch engages.

* No foaming in the sight glass on the receiver dryer.

* Distribution flaps seem to work ok. Don't know about blend flaps.

cheers Warren

 

Common for them to seize. Sometimes you can bring 'em back to life with aerosol proudcts. Check the vacuum hose, of course. It might be broken or disconnected. No vacuum=open heater valve. With the dial set for cold air, the hose should have vacuum to open the valve






Not on an '89. Earlier cars have a tie-in between the a/c compressor and the aux fan. On your car the aux fan is strictly coolant temp controlled








You'll need to get the refrigerant part of the system checked






Well you'll obviously need to check the blend flaps. You can put your hand on the servo motors and feel if they are operating.

I have "fixed" a couple of these systems by cleaning all the tiny connectors...which tend to get corroded. Also, the grounds on either side of the main climate control case get rusty. If the blend flaps are not operating I'd start by cleaning all the connections and grounds and go from there. It's not very pleasant work...a couple of them are wayyyy up high in the dash.

Hope this helps a little. Post back if needed.

Cheers
DD

 

Doug how can i tell what my 1975 AC has for freon, if it has been converted to 134a or still 12.
it has old style screw on fittings, not push on.

i suppose ,recover and vac, and add 134a, anyway.

 

The adapter fittings are usually left in place when an R134 conversion is done so that's your best clue.

Some a/c evac machines have detectors to identify what type of freon is being drawn out.

Cheers
DD

 

i don't mean to try and hijack the thread but i mean more to keep on certain topics because everyone else is talking about them and its useful when someone goes to use the search function.

I tried charging my system the other night, it ran 60Psi ( on the fill gauge) and I couldn't put any freon in it. The stupid retrofit adapter just blew it back out and when i used another one it wouldn't take in any freon It just stayed the same.
clutch is engaging a/c is running at the very end it got a teeny tiny bit cooler but it still didn't take anything from the freon can.
I know the system has a bit of a leak but it should still take a charge.
(car has been sitting for 13 years btw).

 

Dear Doug,

As i see that you guys where talking in this treat about the axil fan I would like to ask this question. Can i rewire the auxil fan in such a way that it is always runs just to give the system that extra cooling. or do you think that it would not help. I'm not sure if the fan works at all because i have never ever seen it run?? How can i test the temp sensor?

many thanks

 

On the '83 XJS shown in your signature?

On that car the circuit is designed so that the aux fan comes on whenever the a/c compressor is engaged...which means virtually whenever the climate control is "on", as the a/c compressor operates in all clmate control modes, even when cabin heat is called for.

If you remove the wires from the aux fan temp switch and jump them together the fan should operate. If not we can run some circuit tests if you have a test light or multi-meter.

The temp switch should be closed at about 94ēC. You can check this with a test light or multi-meter.

Post back for more details if needed

Cheers
DD

 

Clogged expansion valve perhaps?

I'd take it to an a/c specialist so both high side and low side pressures can be checked

CHeers
DD

 

you'd know if it worked, it stays on for a bit after you turn the car off to help cool the system after shutdown. you can hear it.
If you can't hear it thats bad, these cars run hot.

 

kinda what im thinking.
My uncle and dad are both Hvac certified, its just a matter of having the time and a decent day when its not 95 effin degrees out

 

dear Doug & Sidescrollin,

I'm pretty sure the Fan does not work when i turn off the car. I know they run warm after shutdown that is the reason that i open the bonnet (hood) most of the time when possible. I was just reading in the workshop manual how to test it. I was wondering it says specifically do not run engine when testing (why??). Would it not be good practice to just connect the two wires and have it run all the time?? I'm performing the tests now. will post back with news. Many thanks for the help.

 

Just done the test's and NOTHING is happening OMG!! (Panic;-)) what do you all think is the problem the relay?? the fan works because i tested it. I do miss the 50A fuse for aircon motors (keeps on blowing and run out of new ones) but i don't think thats the prob.
let me know what you all think.

 

he guys just a thought could i switch the horn relay with the fan relay to see if it is faulty?? because my horn I do not regular use ;-)).

 

A conventional relay with the 30-85-86-87-87A terminal designations and no internal diodes can be used. A stripe on the relay case indicates it has diodes inside. I don't think the horn relay is the same. It probably lacks the "87A" terminal.

Cheers
DD

 

Yes, but to clarify, only if the coolant temp is hot enough.



Not a bad idea





Without knowing the test procedure they suggest it's hard to say. Maybe it's simply safety related....




I don't see where it would hurt to have it running all the time

Cheers
DD

 

Now after trying your trick it did not do anything so I got myself a new relay. and still nothing what is going on. I don't know any more. I do not mind not having arco but I would like the aux fan to work. please advise on where to look next. anyone?? hope it is'nt the 50A fuse.

many thanks for all prev advice.

 

its probably a good idea to open it and let it cool
if it works after wiring it up yes you could have it on all the time, but id setup a switch just so you don't have to hook up a wire everytime you get in and out of your car.
does anyone know what it reads the temp from? If its different from the regular thermostat perhaps thats gone bad or has a bad connection?

 

I may have missed it, but have you checked the fan fuse located in the headlamp fuse box....on the left side of the engine bay? Also, you might have an in-line fuse for the fan just to the left of the radiator near the radiator mounting panel.

Remember that "checking" a fuse also means making sure the end caps are not corroded. And sometimes a fuse wire breaks away from the end cap so, while it hasn't melted, it isn't making contact, either.

If the fuses are OK there are some circuit tests to run through but you'll need a 12volt test lamp or meter. Shout back on that.

Cheers
DD

 

The aux fan switch reads directly from coolant temperature. On the old V12s the switch is located in the coolant elbow that is attached to the water pump and closes at about 94ēC.

Cheers
DD