Im throwing this out there to see if someone can shed some light on it. I went to work 3 days ago and the A/C was blowing just fine when I parked the Jeep, but when I came back I noticed that it wouldn't blow at all. First thing I did was pull the blower and noticed it was really stiff so I replaced it with a new used one. Nothing. So I checked the resistor, its in perfect condition. Looked at fuses, all good including fuse 20 under the steering column. So I pulled the MultiMeter out to check voltage, Im getting 12-13 volts at the motor connector, and the motor is fine according to the MultiMeter and 2 9volt battery's, everything should be fine and I'm getting good grounds but the blower still will not turn on. I should add that its analog temp and not the auto dual zone, and the relay is inside of the control panel on 2002-2004 WJ's and thus not accessible without pulling the controls all apart.

 

The blower motor is wired hot and the resistor and dash controls form the various ground paths to control speed. You say the resistor is in perfect condition, but did you check it electrically? Is the connector melted? The resistor is mounted in the airflow from the fan to cool it and without the fan running, it can overheat.

 

Yes, save for a little discoloration it could be brand new if I didn't know otherwise. When I said perfect I meant that it only looked a little yellow on the ceramic no micro cracks it either. The connector and pig tail are not melted, and my multimeter show continuity through it. I guess it helps that I almost always run it in high so its pretty well been bypassed its whole life. This whole thing has me scratching my head, I have good connections in the plug to the terminals on the motor and I'm getting power at the plug too. I literally can't find anything wring with it. Ive even pulled the switch panel out of the dash and pulled it apart, the really is switching just fine.

 

Continuity isn't the whole story. Are you sure the resistor segment aren't shorted together? Do each segment show a different resistance? Does the blower run if you ground the wire coming from it? The blower should run even if the entire resistor is shorted or bypassed, as long as the circuit is grounded thru the blower speed switch and the mode selector not being in the off position. I'm going to look at my circuit diagrams.

Okay, if you have 12v at the blower with the key in the run or accessory position, the blower relay is on. The other wire from the blower motor goes thru the resistor to 4 terminals, one for each speed. From there it goes to the fan speed selector switch. The high speed (4) bypasses the resistance coils of the resistor. From there, the circuit goes to the mode selector and is grounded in any position except "off." It may be possible that the grounding circuit has a break in it somewhere after the resistor, either in the mode selector or the wire connecting it to the speed switch. I can print and post that page of the FSM if you'd like me to.

 

This Page is identical for the WJ and XJ

 

Thanks for the help, but I have a completely different diagram for the WJ

I’m looking at the conector on Terminal H because I believe that to be the ground on the motor. From there I believe I’m going to check connections in c1 and c2 that are located at the back of the control head. Hopefully I find my short in one of them.

 

I’ve tested all the connections from the hot to ground, getting 12 volts with the key on, I tested the connection from the blower to the resister and it’s good, I’ve checked for different resistance at each of the speeds for the resistor and they are all different like they should be. The only thing I haven’t been able to do is ground out the blower. This is extremely frustrating.

 

It's possible the circuits are different for the 03 in which case I can't help you.

 

You said you have not been able to "ground out the blower". Did you mean to ground it manually or via switched control circuits?

If you have not attempted manual grounding then briefly, from the motor ground terminal, bypass resistors, controller, etc, with a jumper to ground. Any fan motor reaction? If yes, then it's likely due to your controller's burnt switch contacts....

 

Yeah, it looks like they switched to a solid state controller instead of a mechanical switch. Leave it to Chrysler! I see notes about "drivers" on that circuit diagram.