I can't seem to get the blower fan to work on a 2001 xj. Already changed relay and blower motor resistor. Even tried a different blower. Both blowers work when run directly from battery. And the wires to the blower are both getting right around twelve volts. Still, it won't spin when connected to the motor wires. Any suggestions?

 

umm.. "And the wires to the blower are both getting right around twelve volts."? That's confusing Check the speed selector switch on the dash? The highest speed setting should send full battery voltage to the motor; it doesn't route thru the resistors.

 

That's what is coming from the wires that go to the fan when it's on the high setting. Without the engine running.

 

The blower circuit is looking for a ground through the climate control panel switch selections. See schematic below.

Do the climate control panel lights come on with the headlamp switch on? If so, the ground circuit for the blower and the lights from connector C1, pin 1, to ground point G108 is intact. If the lights don't come on, the ground circuit may be open.

Does the blower work on any speed when the Mode selector is in any selection but OFF?

Answer thes questions and get back.

Here's a schematic of your HVAC Blower circuit.




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The switch controls only the ground to the blower motor.

 

I can't tell if the lights work currently it's far too bright outside. But no, the blower will not come on for any of the settings.

 

The blower motor won't run, however, the engine responds when it's in any of the ac modes or the two defrost settings.

 

If your AC Compressor is engaging when AC is selected that should point to the fact that the ground circuit from connector C1, pins 1 and 6, are intact to G108.

The center (Mode Selector) **** also selects vacuum routing as well as select electrical routing (shown in the schematic).

It's rare that the whole speed selector switch is bad but is possible.

You can pull the climate control panel back far enough and unplug connector C1 and do some resistance readings. See pic of the back of the panel (Vacuum harness removed). C1 plug in is on your right. The pins are numbered from the top. Pin 1 is the top pin and 7 is the bottom pin.

Placing your Ohmmeter (-) probe on pin 1, and (+) probe on pin 5, select #1 fan speed. You should read continuity. Referring to the schematic, repeat the tests for each fan speed, still using pin 1 as the ground (-). You should see continuity for each fan speed. If not, the speed selector switch is defective and the climate control panel needs to be replaced (Ebay).

 

There isn't actually an ac compressor in the jeep. Someone took it out before I bought it. The hoses are just hanging disconnected. I'll test the switch like you said. But I guess I should point out there's an aftermarket instrument cluster (that was sticking occasionally, I thought it was maybe cause of the cold), the fan randomly worked one time a few weeks ago for a few trips. All speeds, and all settings.

 

There is continuity between the pins for the fan speed selector. Seems right according to diagram. I'm thinking you might've been right with the ground assumption. Now, to find said ground.

 

Use your Ohmmeter on the C1 connector this time. Go from pin cavity 1 on the connector to a clean, unpaintd, structure on the dash. If you have continuity that circuit is intact, if not, there's an open in that circuit somewhere. G108 is burried up inside the dash on the far left side, by the Headlamp Delay Module. Hope you have continuity otherwise I will suggest tapping into the ground wire (C1, Pin1) Black/Violet tracer wire, to a new ground you will create nearby. Otherwise you will have a hell of a time finding the open in the existing wire.

Check and get back.

 

There is also continuity between pin one and the unpainted structure.

 

Could you explain in detail how you determined that both wires to the blower are getting 12 volts.

Refer to the schematic. Blower connector pinout = Pin cavity A is power from the relay and pin cavity B is ground through the resistor block/fan speed selector.

 

I'm sorry, didn't mean both wires are getting twelve volts but when you connect them via the ohmmeter it shows 12 volts dc.

 

I take it you connected pin cavity A to pin cavity B on the blower connector using the voltmeter leads and you read 12 volts. Correct?

If so, you've verified the power circuit works (Pin A) and the ground circuit works (pin B).

If the above is correct, there's no reason the blower won't work, unless the pin cavities in the blower connector are shoved back too far or the pin cavities are enlarged from shoving meter probes in them.

Do a close visual examination of the pin cavities in the blower connector.