LiamLikeNeeson

(1989 4.0L)

So my mechanic and I were refilling the refrigerant and the compressor clutch wouldn't engage. I know it works because I tested the compressor by jumping it to the batter for a brief second and it engaged. He didn't want to put more refrigerant in because the pressure was starting to go too high so we have to hope it's electrical. We can't seem to find the problem and we checked the relays near the coolant tank and they were fine but doing the test method of putting a paper clip to jump both pins on the plug that is below the compressor didn't work.

Is there a fuse somewhere under the dash for the A/C compressor that would stop it from engaging? We couldn't find one and we tested all of the fuses and they were fine. Any guidance would help because my mechanic is very busy working on the Furious 8 cars so if I want to get my A/C working anytime soon I will have to fix it.

The air blows when I turn the A/C switch to Max, Norm, or Bi-Level, and also my heater works very well when I turn it on.

My apologies if I left out any information needed to understand what's going on.

RED RIVER

High pressure switch or low pressure switch. There are some good videos of how to check and replace them on line.

Turbo X_J

If the system was empty you (and your "mechanic") should find and repair the leaks before killing anymore baby polar bears...

freegdr

Check for constant power. Try jumping 30 and 87 on ac relay plug see if it kicks on.

LiamLikeNeeson

I'll check it out thanks!

I forgot to mention that the refrigerant we are putting in has a dye in it so we can find the leaks but the last thing I want to do is kill more baby polar bears!

Ok will do thanks!

Cane

it usually leaks at the evap core inside the dash area, so you won't see any dye in the engine bay, or outside of the jeep for that matter.

LiamLikeNeeson

Is it something you can smell if it does leak inside the evap core?

JPXJMOAB

Not really. You'll need a beeper style leak detector. That'll show the leak with an evap core.

LiamLikeNeeson

I think I'm just going to bring it to an AC diagnosis place lol

93XJeeper

Just did this a couple days ago, mine was dong the exact same thing, first off, use a multimeter to see if your getting 12v at the compressor wire. If not, when I did mine, I couldn't find a fuse anywhere, turned out that the fuse box lid under hood was mislabeled. One of the mini fuses is actually for the AC and was blown. Go through and pull and check the mini fuses, if should be one of the 15a fuses but check them all just in case.

93XJeeper

Here's pics. It turned out to be the 15 amp mini fuse labels aux lamps. Or maybe it was the one labeled ignition. But it was one of those two.

93XJeeper

Here is the correct fuse box lid that I found. As you can see, it says AC Comp instead of Aux Lamps