Blower Motor and Resistor Pack
It's a common problem; one that's posted numerous times on just about every Jeep forum out there. "My fan doesn't blow anymore....except on High!" I've seen and heard of people who go through countless hours of troubleshooting and throw money at it to no avail. Tell you what - if you just have money laying around that you want to throw, by all means please throw some my way. Otherwise, follow these steps to fix the problem.
The fan control on the Jeep Cherokee (as well as the YJ and TJ/LJ Wranglers, and ZJ Grand Cherokees) is a simple circuit that controls the fan speed by changing the resistance going to the fan. At higher resistance, the fan turns more slowly. At full speed, the resistor is taken out of the circuit, which is why we know you've got a dead resistor pack when the fan only blows on High.
Sometimes this can be caused by problems with the blower motor itself. If it's an older motor or is very dirty, it can help burn out the resistors. I never had to replace the resistors in my white '96 Cherokee although I replaced the motor when it began to drag. The red '96 seems destined to be a needy one, so I decided to replace the blower motor when I realized the resistor pack was dead.
 The blower motor is on the firewall behind the windshield washer reservoir. |
 It's hiding back there somewhere |
 The blower motor |
Disonnect the negative terminal of the battery before doing any work on the electrical system.
The windshield washer reservoir and Power Distribution Center need to be removed to get at the blower motor. There are two bolts along the firewall and a third at the bottom of the reservoir but I found it easier to remove the bolt holding the front leg and just push it out of the way. Don't forget to disconnect the plug on the bottom of the reservoir as you pull it out of the way.
Unplug the blower motor from the harness, and then remove the three 1/4" screws from the motor housing. There is a rubber drain hose under the motor that will pop out when pinched near the housing. Also watch out for the rubber gasket behind the housing, so be careful not to tear it while removing the housing.
 Motor housing with attached fan. Note the gasket |
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 Missing blower motor - note the resistor pack inside the hole on the right side |
The squirrel cage is held onto the motor shaft by a round spring clip. Squeeze the ears of the clip with a pair of pliers and remove. Pull the cage off the motor shaft and install it on the new motor. It probably wouldn't hurt to clean it up a bit first, either.
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created: Jan 17, 2011