Just bought the XJ6 last week and 2 days later, the a/c quit. I did some research and found/did the a/c self-test and reset and the a/c magically worked again.

Yesterday, the a/c started to work intermittently, so i did the a/c self-test, but no change. I "tapped" (handle-end of a screwdriver) on the trinary switch and the a/c seemed as if it returned to normal operation.

Unfortunately, i gave the trinary another tap and *now*, the larger of the two radiator fans is on "high speed", all the time (even with the key/engine off).

Anyway, so I turn the a/c switch and a/c blower on and observe the compressor. The clutch kicks on for 2 seconds, then off for 5 seconds - it cycles like this constantly, but no cold air out the dash vents. I show about 75 PSI using one of those cheapo gauges that comes on a can of freon.

Is there a way to test the trinary to ensure it's working/not working? Also, when changing out the trinary, does the a/c system have to be evacuated?

 

I see no way to edit my original post, so replying to my own post ...

I failed to mention I see an error 23 doing the a/c self-test:
23 - Refrigerant Pressure Switch Open / short circuits. Low
gas charge*.

 

The 2 fans run in series on LOW and in parallel on HIGH so I would say that one fan is deceased or the fuse is blown.

There is a TSB for the low fans to run anytime the ign switch is ON.

If you don't have an electrical guide or understand how the system operates, then this is going to be a long thread.

bob gauff

 

Although there can be other causes, rapid compressor cycling is what a/c systems do when they are low on charge. BTW, it's not a good thing, your compressor is seeing some pretty high temps while it is cycling that rapidly, so if it were me, I'd leave it "off" or pull a fuse until I got it sorted.

I believe the Ford systems of the mid-90's, fresh off the conversion to R134a had schrader valves in the switch ports, letting you change switches without losing your refrigerant charge. Whether or not implementation of that practice made it over to Jag by '96 (or was previously resident thereon) would be pure speculation on my part. My guess is that everyone was putting schrader valves in their switch-ports....

 

@Bob ... both fans are running, even with the ignition off, and running at the higher speed. I have the new trinary switch ... even though it's not installed, I've plugged it into the harness and the fans don't run. so I suspect the trinary still installed is bad.

I've obtained a factory repair manual and electrical guides, so have an advantage now. Something interesting I've found in the electrical troubleshooting guide:
"In ambient temperatures above 35*C (95*F), the system may log fault code 23 as temporary high pressure can exist within the system". ... Does this suggest the A/C system would go into some sort of "limp mode" to protect itself in ambient high-temp scenarios?

Down here in Houston, TX (Texas-wide, for that matter), we've been experiencing high temps for weeks (with no rain). Today's forecast is 101*F. Yesterday, I sat in the Jag and touched the "external" temp button and it showed 100.

@aholbro1 ... I currently have the trinary switch disconnected, otherwise the fans would be running all the time - with the trinary switch disconnected, the a/c won't run.

Here's the currently-installed trinary and the newer one - it simply unscrews to remove and screws on to install - don't see how it can be replaced and the system not purge:

 

hello, jag lovers 1995 XJ6 w/183k miles, i'm experinecing somewhat of same problem, as bob, but my problem is the fans wont kick on to high ,panel say "LO" even when manual is selection and i turn knob to high?? Do the Trinay switch control fans
Geno

 

Caldercay,

I scored a 109 deg F on the display of external air this week! (black car sitting in black parking lot) but it tempered to about 103 once underway...

My a/c is working flawlessly so I'm going to let you do all the experimentation on yours!

However, if you look at one of your service ports, either high or low side, it makes no difference, you'll see they have fitted schrader valves just like the valve stems in your tires. Many manufacturers were putting those in their switch ports as well, and the switch will have a little button in the center to depress it as the switch is screwed on. I can (and have) swap switches on my Ford cycling clutch orifice tube systems without any effective loss of refrigerant (a very slight "psshhhht" at most)

The high-pressure function disengages the compressor before head pressures exceed the pressure-relief-valve setting. This is something you may see after extended idling with a tailwind on a 110+ degree day....or idling whilst parked right up against a wall....or if your condenser were clogged with bugs, mud, or whatever. Most all R134a systems were fitted with a high-side switch to perform the same function, though not always a "trinary" one. Haven't studied the XJ6 system and controls in-depth (remember? mine works fine) but trinary means you have 3 switches, essentially in there, and I suspect one is to activate the fans to low-speed, one to high speed and a third to secure the compressor just shy of the PRV value.

You are correct that the switch is an easy change...If you could only confirm that there is a valve under it.....otherwise, you are looking at changing switch...then pulling a vacuum for 30 mins...then total re-charge....

Good luck and keep us posted on your progress...

 

@Geno ... yes, the trinary pressure switch controls the radiator fans.

To all: I changed out the trinary pressure switch, and yes, fortunately, there is a schrader valve in the fitting, so no loss of freon.

So, that fixed the issue with the fans running all the time (the problem I caused by tapping on the switch). I still got an error 23 on the a/c panel (after replacing the switch), which states, "pressure switch of low gas".

I did a static test with the gauges and got a reading of about 150 (PSI) on low and high side, then did a running test - high side about 250 and low side cycling (compressor cycling) from about 25 to zero, so put a (18 oz) can of r134 on the service port and got the low side to [almost] a constant 30 PSI ... back to cooling !

I have a feeling I might have a leak - we'll see if she continues to cool ... thanks for all who responded !

 

Thanks for updating with the solution and confirming the schrader v/v does exist.

I hope the cooling continues without a leak. Fingers crossed!

 

So, how do you do this self test? I am having AC problems and this seems like a good way to start.

 

https://www.jaguarforums.com/forum/x...est-x300-8039/

 

Congrats on the fix and thanks for posting it.



If you DO have a leak....AND if your luck is otherwise good and it's in a VISIBLE place...there should be a trace of oil or oil/dust in the general vicinity. If tucked away in the evaporator or somewhere....yikes! Obviously, check all joints/hose connections first and also the condenser which is up front and exposed to stone damage, etc.

 

I have a paper TSB somewhere that has the VIN split when the switches have the Schraeder Valves in the switch ports. The early X300 did not have the valves if I remember correctly. I'll look through my 3 ring binders to see if I can find it.

bob gauff

 

11.3 - Climate Control Test and Diagnosis
The climate control system is significantly different from earlier XJ40 models in that all flaps and valves are electrically operated, with no reliance on engine vacuum. The system is of the 'constant air flow' type, meaning that fan speed is adjusted based on road speed to maintain the desired flow rate.

The system can be put through a self-test procedure as follows:

Warm the engine then switch off. Press both 'Auto' and 'Recirc' buttons and hold whilst restarting the engine.

All the panel LED's and LCD display will flash. Any areas failing to flash suggest a problem with the bulb, display or function in that area.

Press 'Auto'. If the display is zero, then no error codes are stored. Any other number is an error code. Use 'demist' to cycle through up to five stored codes. Press 'demist' and 'heated rear window' to clear a displayed code. Code 23 indicates low refrigerant pressure.

Press 'Recirc' to enter diagnostic mode. Repeatedly pressing 'Face' will step through the 8 different combinations of vent actuation and you will be able to hear and feel vents and fan operating.

Pressing 'Off' will restore the unit to normal operation with the default settings.

List of control codes:

0 - Normal Operation - No fault codes present, wait 30 seconds for system
self-check.
11 - Motorized In-car Aspirator (sensor element)Open / short circuit. Panel
fault codes are not stored for blown aspirator failure of motor.
12 - Ambient Temperature SensorOpen / short circuits.
13 - Evaporator Temperature SensorOpen / short circuits.
14 - Engine Coolant Temperature InputInstrument pack output.
15 - Heater Matrix Temperature SensorOpen / short circuits.
21 - Solar SensorOpen / short circuits.
22 - Compressor Lock SignalOpen / short circuits. Low gas charge, low
compressor oil, loose belt.
23 - Refrigerant Pressure SwitchOpen / short circuits. Low gas charge*.
24 - Differential PotentiometerOpen / short circuits.
31 - LH Fresh / Recirc. PotentiometerOpen / short circuit in pot.
feed. In certain circumstances, the motor can over-travel and log further
faults. Cycling the ignition two or three times can cure this.
32 - RH Fresh / Recirc. Potentiometer
33 - Cool Air Bypass Potentiometer
34 - Defrost Potentiometer
35 - Centre Vent Potentiometer
36 - Foot Potentiometer
41 - LH Fresh / Recirc. MotorCheck for short / open circuits in motor drive
lines. Motor flap sticking / jammed.
42 - RH Fresh / Recirc. Motor
43 - Cool Air Bypass Motor
44 - Defrost Motor
45 - Centre Vent Motor
46 - Foot Motor

Other symptoms that don't generate codes

No heat - Airlock in system. Water pump inoperative. Water valve stuck
closed. Faulty engine coolant thermostat.
One vent failing to open or close - Broken linkage.
Poor airflow - Blower motors - incorrect operation (eg fuses blown).

 

I'm pretty sure I have a leak somewhere. Yesterday, low-side pressure was cycling from about 5 to 20 PSI and the system wasn't cooling. So as I was putting in a 12oz can of r134 ... the low-side pressure was approaching 30 PSI (high-side about 275), when the compressor blew freon out, I assume, through a purge valve of some sort (?).

Unfortunately, I'm flying out this afternoon to PA and returning Wed night, so can't look at it until after Thur.

 

Hi, everyone,, its not my radiator fans its my ac fans wont kick on to hi, i can hear and feel the housings there in up under the dash when in the manual mode i call it, when i manually turn the fan knob, panel say LO, so what do you all think. Acouple of years ago i found a broken wire on the 2 wire switch located on the as tubing right before going into firewall, there another 4 wire switch reight next to it. just had a thought from some posts, humm wonder would low freon possible casue this?? nut heck when i use auto button crank ity to 66 degress air is very cold, just no fans running at high. could there be some fan relays, that have failed???
Geno 1995xj6