Jaguar Repair: AC compressor is always on. 1985 XJ6, air temperature changes, thermal fuse

Question
QUESTION: When the Climate control is off the compressor stays off, but hen I turn it on any position (low, auto, high), and no mater what temperature I set up (65, 75, or 90) it always stays on.

The air temperature changes accordingly to the set temp on the climate control, but even when its set to 90 deg. compressor is still on (clutch is engaged).

I checked the wires Yellow w/brown tracer wire from the Ranco therm to a brown w/yellow tracer wire from the fan. Both wires (yellow/brown and green/brown) show ground (-) when the fan is set on off, and +12v when the fan is on (on any position) and no matter what temperature is set on the climate control.



I am new to the car and I am afraid that if the compressor is running constantly it may eventually burn up really quick. Is that normal, that the AC compressor stays always on no matter what temp. is set up, or maybe its controlled by something and should turn on and off accordingly to set temp. on the climate control knob?

Also I noticed that the previous owner removed the Thermal fuse and put regular 15A fuse in its place. (The superheat sensor is also removed).
Will this setup work to protect my compressor from overheating? What is the easiest way to fix it? (Anything other then replacing compressor with new superheat sensor and adding thermal fuse?).

Thanks
Sebastian


ANSWER: Hi Sebastian,

Yes, the compressor and AC is on all the time even when heat is on. Jaguar did that to dehumidify the air. They use all of the vacuum doors to blend the correct temp that you set.
Howard

---------- FOLLOW-UP ----------

QUESTION: Also I noticed that the previous owner removed the Thermal fuse and put regular 15A fuse in its place. (The superheat sensor is also removed).
Will this setup work to protect my compressor from overheating? What is the easiest way to fix it? (Anything other then replacing compressor with new superheat sensor and adding thermal fuse?).

Thanks
Sebastian

ANSWER: If you are worried about it go to Jaguar and purchase the missing sensor etc. Or are you saying you have a different type of compressor on the car that does not have any sensor?
Howard

---------- FOLLOW-UP ----------

QUESTION: Yes the compressor is different, with no superheat sensor.

Answer
If you want an overheat protection for the compressor, you have an engineering problem. You will first have to determine what is too hot, then you will need to locate a sensor that can disconnect the compressor at the target temp. To even start this you will need to contact the manufacture of the compressor you have to get that info. Good luck.
I have several series III Jags and all have failed original compressors and I am rebuilding one of the cars now and have mounted a Sankyo compressor but I have no plans to even try to install an overheat protection system. I will have an inline fuse to the clutch though. Wish me luck.
Howard