Hi, I just bought a 1993 jeep cherokee at 156k miles for $1,300. When I got it, the a/c and radio didn't work. Blown alternator, and blown heater core. Simply put, i knew it would have problems. So far I've fixed the radio and am in the process of addressing the alternator. My problem is the A/C. The fan will only run if it is on the heat option. Low to high it runs. If i move the slider from heat it shuts off. I think the lack of alternator may be the culprit or atleast one of the contributors. Any ideas would be greatly appreciated!

Also this is my first car so im new in the car world but have been doing extensive research about cherokees among other things.

 

The heat selector is actually part of the circuit to power the fan. Chances are it needs replacing. You may also find that the wiring connected to it has melted its connector. Your best bet is to pull the switch out and have a look if it has melted.

If all looks fine, pins 1 & 4 are the power in/out for the motor, check for continuity with a multimeter across those 2 and cycle through the vent selections and you'll probably find increased resistance or open loop when not on Heat.

While you're tackling this issue, it is a good idea to pull the blower motor out and check that it spins freely and makes no bearing noises. A bad motor will put extra strain on the circuit which causes burnt contacts and melting connections.

 

Forgot to add my picture.

 

I just got around to it today. It is in fact an electrical problem. Wires have been kinked in the back as if they were shoved in there. Got it to blow on the vent option. Low to high so that's a start.