Experience Dealership line mechanic on MG, Triumph, Jaguar for 15 years, Instructor in commercial mechanics school 2 yr. Product information manager for piston and valve manufacture, Instructor & hotline answer man for import car parts importer 15 yrs.
Organizations Associate member SAE
EAA member
Publications Import Car magazine
Education/Credentials ASE Master Auto with L-1 certification up to 2000
Question Hi Howard,
I’m writing this as your responses to other people on line are very professional and comprehensive! The needle on the temperature gauge of my 1984 jaguar XJ6 does not go up to full operating temperature (i.e. to 85 / 90 degrees which is midway on the gauge or start of the green band). It only ever goes to approx. 75 degrees no matter what the driving conditions are. Would this be a faulty/inaccurate gauge or an indication that the engine is not running at optimum temp.? Any way of testing for this or what steps I should take?
One other problem that I have with the car is that the a/c has stopped working. It just blows luke warm air when I turn the knob around to the coldest position. Before it stopped working I had noticed that the a/c compressor was very noisy anytime the a/c or heating system was turned on (which was very annoying because to passers by it sounded like the engine was very rough!) The questions I have in relation to this are; is this level of noise normal for a/c compressors? Do you think that absence of noise from the compressor means the compressor needs to be replaced? Do you think the compressor is the reason for the a/c not working?
Thank you for taking the time to read this and for any help that you can pass on.
Frank.
Answer HI Frank,
The sending units are in the end of each fuel tank behind each tail light assembly. Run the tanks low on fuel and you can jack the rear up and remove the tail light assembly and remove the sending units and with each out, reconnect the wires and tape or stuff a rag in the opening in the tank as you don't want a spark around the fumes. then turn on the ignition and hand operate the arm on the sending unit to see if the gauge goes full to empty. If it does not and the arm is free to move it's full travel it is most likely the gauge because the sending unit is a wire wound resistor and is most likely unable to change in resistance. The gauge uses a full 12 volts and does not use a voltage stabilizer. With the ignition on disconnect the light green wire from the sending unit and note which way the gauge needle goes. If it goes up past full, it is possible to add an adjustable resistor to the wire and trim the reading without purchasing a new gauge or sending unit. If the gauge goes down below empty that can't be done. I have been able to do that on other cars but have not tried it on a Jag yet.
If you don't want to do all of that and can wait, I have a jag that has that problem and I have intended to try it. So I will do the resistor test soon.
