Ok so when i got my 93 xjs i noticed that someone had run a jumper wire from the AC relay to the electric fan relay. A common fix i know. It worked when i turned on my fan to high, with the temp all the way down, but then it stopped. Im wondering if my Freon or r134 leaked out and now the low pressure sensor is causing it not to let it actuate. I just got to trying to look at it, and i am kinda stumped. I did see that one of the previous owners had replaced the thermal switch in the radiator and im wondering if that was part of their troubleshooting before they ran the jumper. I am getting power to the fan relay and the AC relay. When i jump power at the fan relay it runs nicely. Also when i jump power at the AC relay the fan runs. Id like to have it running the way it was designed, and would prefer not to just put in a swich to cut it on and off. When i have the fan relay in the socket, and touch the two leads from the thermal switch together, nothing happens. However with the switch unplugged and jumping power the fan runs! Anything anyone can think to check? Or any thoughts?

 

I have a1993 and had problems with the fans. My solution was to rebuild the circuits on the fan.. It's an easy job one big transister an a couple of diodes and a resister or two. Hardest part is pulling the fans out of the car. Every thing else in the a/c system is stock and working fine as Jag designed. I did not use R.21 but use a substitute product. I think it was propane based because the government stopped its use. Still use it in the car and that is over four years ago and it cools down to Greenland temps. If I were you, I would return the car to Jag spec by following the a/c schematic. Good Luck

 

Timeisrelative - My cooling fan stopped working on my 96 with the AJ16 engine. I did the same checks as you and the fan works perfectly when power is supplied, so I'm assuming it is the thermostatic switch. The original style switch with the leads attached is impossible to find, so I have ordered a switch from a British parts supplier in the northwest that I think will work. It is for a 1978-1980 Spitfire and is sized M22 x 1.5, which members on this forum have said is the correct size. The temperature range is closed at 92C (198F) and open at 87C (188F). Price was $9.80 and includes the gasket. I'll let you know how it works out in about a week or so. In your situation, you could restore the always hot wire (not ignition switched) to your relay and do a manual switch across the thermostatic switch to operate your fan. Just remember to turn it off when you park the car.

 

Yeah thats part of why i want to get it back to proper functionality. I don't like to have to remember to turn off, or on for that matter, a fan to cool the engine. Im sure i could easily get it to work that way, but its not right. Not really a purist, but something's should just work as designed.

 

Just wanted to see if you had any updates on the spitfire switch working or not

 

Those 22mm switches are very common, lots of VW/Audi/Saab products used them, with various on and off temperatures.

 

Timeisrelative - I think I may have replaced my thermostatic switch needlessly. I put the new switch in, went for a drive on a 90 degree plus day, the temp needle went above N and the fan did not come on. It got me thinking, so I put the old switch in heated water and it closed at about 207 degrees. That seems high to me, but the switch worked. I then went to the car, connected the OBD2 bluetooth reader, and ran the engine at idle with the AC on. My OBD2 reader said 196 degrees when the needle was in the middle of the N. I increased the rpm to 2000 and the needle slowly moved past the N and the fan still did not come on. I revved the engine a little more and finally the fan came on at about 207 degrees. The needle was about a third of the way between N and H when the fan came on. The moral of the story is I think this is how the facelift cars were designed and I'm not going to worry when the needle moves past the N as long as it doesn't get halfway to the H. The specs say the switch closes at 198 degrees, so the radiator is obviously cooler than the temperature sender unit on the thermostat housing.

 

My downfall is that my temp gauge goes all the way past hot as soon as i start the car so i have no real onboard visual right now. My oil pressure gauge flaked out now too, as it jumps all the way past high as soon as the car starts too, as in almost to a 5oclock position on the dial. Im figuring its a ground or printed circuit issue, just haven't figured it out yet. Also my 93 unfortunately doesn't have the obd capabilities. It still has the jag reader connector. I have checked my engine temp with my infrared thermometer and it reads about 190ish after a drive. Part of me is tempted to just run a mechanical set of gauges, but that hasn't happened yet