As the title says, the heater fan has stopped working on speed 3. This is on my 2001 XJ. All other speeds work fine. What is the best way to figure out if the resistor has failed or if it is the switch itself, other than just replacing parts?

 

The switch may be defective but that would be rare. I would want to check the electrical connector on the resistor block. It has a habit of melting.


Here's a schematic of the blower system:





You'll have to remove the kick cover from under the glove box then you can get at the resistor block.

 

Thanks. I'll be sure and check the connector.

 

connector was melted. Thanks for the heads up on what to look at first.

 

Be aware that there are aftermarket connector/pigtails out there but the wire gauge may not be what's needed.


Note that in the schematic the wire gauge for three out of the four are AWG 14, and the fourth, high speed is AWG 12.


Shop around for a connector with the proper size wires. If required, the high speed wire can be changed out for 12 AWG if the only thing you can get is AWG 14 in all four places.

 

Finally got around to replacing the connector at the resistor bank and the blower still does not work on speed 3. I checked the continuity across all of the resistors as well as the wiring from the switch to the connector at the resistor bank. Took the switch apart and nothing looks burnt or out of place. I'm stumped.

 

Refer to the blower circuit schematic and the pic below.


Remove connector C1 from the climate control panel and the blower resistor connector.


Using a digital Ohmmeter set to 200 Ohms, measure the resistance between connector C1 pin cavity 3 (Light Blue wire) to pin cavity 3 (Light Blue wire) in the blower resistor connector. You should see no more than 5 Ohms resistance. It is helpful yo use safety pins to probe the pin cavities.


If you read less than 5 Ohms resistance the circuit should be considered okay. If you read OPEN or high resistance note that there are two connectors between the climate control panel and the blower resistor. there may be a fault in one of these connectors. C209 is behind the glove box and C201 is centered near the floor under the dash - it is a bolted connector.


You can check the blower speed switch circuit inside the climate control panel by checking for continuity between pin C1-3 and pin C1-1 with the blower selector in the speed 3 position. Again, you should see continuity.



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