94 XJ AC Runs on all Settings

I spent a lot of time searching and came up dry, so if you have a link to an existing thread, please post it.

It only blows thru the defrost, so I have to run down the vacuum leak, and it runs the compressor on all control settings. I don't know if those two are related.

I hate to buy a new control @ $140.00 and find out it wasn't the issue. Thanks!

Vacuum's gonna control the mode door, but not the electrical signal to the compressor, I'm thinking. Even if there's no vacuum to the mode door, if you turn the knob to a different setting, it will cut power to the compressor in normal operation. I would look for any vacuum issues first just to eliminate those, and then find the wire that supplies voltage or ground to the compressor circuit. Shouldn't be too hard to pull the control head and backprobe the connector. You can use a test light to see if that circuit is energized at the correct times.

I don't have an FSM with me, so I could be wrong, but those are my thoughts.

Chris

Mine's 96 had a short, melted the plug in, wires all mucked up. Got a scrap yard harness chunk, re-did it, presto!. That was 5 years ago, and I've got to do it again, unfortunately.

Is the clutch seized?

Thanks for the input. Compressor/clutch work fine. After plugging a few vacuum leaks it now works great out of the vents in bi-level. It blows out of the vents on heat also. Kinda screwy, but it's progress. I will play with it a few days to see if the ac is off when it is supposed to be.

Hoss79 said:

Mine's 96 had a short, melted the plug in, wires all mucked up. Got a scrap yard harness chunk, re-did it, presto!. That was 5 years ago, and I've got to do it again, unfortunately.

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This is what I was thinking.
Hardly see a older XJ which doesn't have some issues with the ac/heater wiring.
My first guess the wiring overheated and melted the plug or wires somewhere . I'd pull the radio and take a peak at the wiring situation. The plug in the middle where the ac selector is at should be the on to look at.

You should be able to pick up a used ac control assembly for a fraction of the $140 for a new unit.