I’m kind of at a loss as to why this is happening, but at the same time I think I know what’s going on.

So let’s go back a week to when it first blew.

I was cooking about 80 on the interstate. My girlfriend was with me, and as we were going down the road, I felt my A/C go warm. At that time, I tried to switch the modes in hopes that it would turn on, but no dice.

So, I went to my work and started looking at diagrams in the FSM. I eventually found out that fuse #11 (15 amp) was blown. Swapped it for a new fuse, and the compressor clutch engaged.

So, let’s flash forward to what I was doing that day.

I was planning on swapping my intake for one that was ported and had the 4.0 TB on it, as well as bored out to match the TB. Everything was going good, until I took off the belt and my alternator clapped against the block. Turns out, the lower alternator bracket snapped in half.

I think that when the bracket snapped, it caused some sort of voltage jump and fried something. Because now, after the 3rd fuse and a relay, it’s still blowing.

Now, it doesn’t blow right away. It takes some time to blow, and it seems to blow when I turn on the A/C. From what I can understand, fuse #11 for the compressor clutch is pretty much just for that. It receives power from the PCM when the selector switch is in any A/C position, and then it goes through fuse #11 to power the clutch.

It also goes to the radiator fan control relay, but I don’t have that since I don’t have an electric fan.

So, from my understanding here, it seems that the compressor clutch might be shorting internally, causing that fuse to blow. I highly doubt the PCM is blowing it, since it only supplies a 12v supply to the A/C relay, which then powers the fuse to the clutch.

Is there any way I can actually test the compressor clutch?

 

Either the winding for the clutch is shirting internally, or the wire to it is worn through and hitting something. You can engage the clutch by putting 12-volts to the wire to it. The power to the a/c clutch might also power an aux fan.

 

think I figured it out.

So, it turns out that fuse #11 powers the A/C clutch, speed control switch, and the backup switch (on mine at least). So, I looked under, and I found some exposed wires leading from the reverse switch on the trans, and that was because it had melted from close contact with the exhaust, and I think those exposed wires were shorting to ground and blowing the fuse. So I wrapped them up with electrical tape, zip-tied them away from the exhaust, and drove my Jeep around with the A/C on, making sure to back up frequently and use cruise control. The fuse is still good, and it seems that might of been the issue.

I also had it wrong with how the PCM turns on the compressor clutch. When the slide switch goes into an A/C position, the PCM receives the input to turn on the switch. It then sends a ground to the compressor clutch relay and completes the circuit to power the clutch. Fuse #11 is what supplies power to the relay, not the clutch.

 

Yeah, pretty sure that was the problem. Fuse is still intact after a few days and a lot of miles.