So my newly acquired 94 V12 has a few problems. I'm willing to accept that. It gives me a chance to learn something new about a new car.

I'll just list what I am seeing and maybe someone can find common grounds"

1. The fan setting in the cabin can be set to the off position and there is a woft of air that is audible that comes out of the vents every 5 or so seconds no matter what. Driving, idle, just 'ON' even.

2. The AC compressor seems to be on all the time?

3. The engine runs a little too warm even after fixing an electric fan issue (it is better now than before)...not boiling over but the potential seems there. I'm servicing that as well as modding in the days to come.

4. I have another thread that describes and issue where the engine shuts down on its own at stops sometimes....seems to be only when on the warm side (which is a lot mind you) but it may just be a coincidence on that one. It will still have power and try to crank....just not delivering, I'm guessing, fuel. Not verified but a good guess. I can't even take the car out of park with the key on in these moments. Eventually but just goofing around I get it to behave as it should.

5. The gauges randomly jerk about. Not constantly but quite often....usually noticeable when number 4 is happening.

6. The ABS light comes on from time to time. The brake peddle seems very hard to me as well but pumping the brakes many times and then turning the car over seems to show no light warnings at all....the normal added delay for the light to come off happens but it does come off.

Any ideas on maybe a common or a couple common things to look into?

THANKS!!!!!

 

1. Pull out the switch and test it

2. Probably related to number 1

3. What are the temps and when do they happen? Idle? over 35mph? Do you know if the thermostats are working properly?

4. If it is overheating a part of the ignition system could also be overheating. So you may have fuel that you can't ignite. Fix the overheating problem first.

5. Like you said, related to number 4, if the heat is causing electric issues then this could happen.

6. Idk anything about later XJS ABS and 90s ABS systems are all over the place. Find what sensors exist in the system and diagnose based on what it is the system checks for that can cause the light to come on. Does the accumulator have a sensor?

 

Dan,

The pulsing fan when turned off is often caused by corrosion in the Darlington transistor that is mounted each side of the heater complex and controls the fan speeds. Have a good read through the proper workshop manual and you'll understand its location.

Good luck

Paul

 

On the older systems...certainly '92 and older....the system was designed so that the compressor engaged in all climate control modes, even when heating was called for. The only way to turn the compressor off was to turn the system 'off'.

Except convertibles......some of which were wired to keep the compressor engaged at all times for fuel cooling purposes, even if 'off' was selected on the controls

I'm not sure how 1994 cars were set up, so all the above might be useless, but, OTOH, 'compressor on all the time' might well be perfectly normal

Cheers
DD

 

Some info/pics on the subejct

Air conditioning blower control


Cheers
DD