My heater fan quit working. I don't know if the problem is with the fan or the electrical system (fuse?).

1. Back probe the Brown/Light Green wire and ground the circuit. This should allow the blower to run on high speed. If it does not, replace the controller. Pay attention to the pigtail connection, it is known to get hot and have poor connections. Install connector repair kit part number #05102406AA. Replace the blower motor as well. The blower motor draws high current and damages this connector. Jeep recommends replacing the blower motor controller, blower motor and the repair kit when this happens. YOU CAN ALSO TRY: 1. At the resistor board, ground each wire one at a time and see if each blower speed is working. If not, then it is a resistor problem.

2. If each speed is working then verify the solid Black wire in the C3 connector at the control head is grounded. If it is, then it is a bad switch

If blower motor operates on high speed only. there is a resistor located in heater box by the blower motor. sometimes glove box door needs to be lowered to access. if blower does not work on any speed there is a fuse panel on drivers side by brake pedal under dash. i believe that contains fuse for blower motor should be labeled. if it is blown most likely bad blower motor. if it is not blown u still may have a stuck blower motor but u have to chk for power at b.m. connector

First place to check is fuse box. Look at F-20. It is under the dash, left of the steering wheel.

Here's a link to the fuse box legend...

http://www.wjjeeps.com/fuses.htm

Here's a link to show you where the fuses sit in the box...

http://www.wjjeeps.com/misc/jblock_main.jpg