JeepWoman

Picked up 94 and have a question with no fan speed other than high. Changed the switch as it was burnt toast, did the connections individual because couldn't find one that wasn't. Changed the motor because it was binding up and making noise, changed the resistor as well. Fan will only work on high, any ideas of other things to look for?

PatHenry

Probably have melted wiring or a connector around the resistor. You may have to run completely new wiring if it was burned out that bad.

smooth move

relay?

dave1123

I can only tell you for sure how the heater fan is wired in my 2000 Grand Cherokee, but I'm assuming the XJ is the same. The fan is wired hot with the ignition key on. The rest of the circuits are just different ground paths thru the resistor and speed switch with the final ground in the mode switch. It other words, as long as the mode switch is not "off", the fan is running. The speed is controlled by whichever resistor tap is grounded by the speed switch and high speed bypasses the resistor completely. It not uncommon for the fan to draw enough current to either burn the resistor out or melt the resistor connector, or both. The mode switch is the one that sends the heated air to different outlets by vacuum valving. The temperature is controlled by stepper motors moving the blend door.

This is for the manual heater controls. If any XJ has the automatic climate control (like maybe the Limited), it's all controlled by it's own built in computer module and it has a control module instead of a fan resistor.

JeepWoman

This is what the plug and switch looked like.

JeepWoman

Wouldn't let me add this to previous post.

dave1123

This is on the back of the control panel? Crispy critters! It looks like the fan motor actually shorted and went directly to ground thru the control circuit. That should have blown the fuse unless it was just a heat building high resistance draw. To explain that, I put a 55 watt halogen headlight bulb in a rooftop service light and kept melting the cigarette lighter plugs from the resistance of the contact inside the socket, but not blowing the 10amp fuse. The bulb only had a 4amp draw. It's a cheap Chinese plastic plug also. I went to a 1/4" mono headphone plug and jack in the dash and it doesn't melt because of the tight contacts.

So, it looks like time to run some new wire, unless you can save what's left of the harness. You can get the connector plugs from the junkyard and in some cases order them from a dealer, but lately they don't have them available if they are 10 years old UNLESS the same plug was used on a newer model. If the harness is a separate piece from the resistor to the switch, maybe you can grab the whole thing at the junkyard. I can almost bet this whole situation was caused by a worn out fan bearing. (Which reminds me my fan is squealing on low when it's cold. Maybe I should buy a new fan.)

dave1123

Maybe this will help;

JeepWoman

By that diagram the plug has the 4 wires, but not a ground wire like it shows. There were only 4 wires in the plug.

dave1123

Which plug are you talking about? Is that the blower motor relay? G108 is strictly for lighting and is separate from C201, but C201 has 5 wires in it. The only 2 connectors in that diagram that have 4 wires are the resistor connector and the relay connector.

JeepWoman

Talking about the fan switch it's self. it has 5 prongs, but only 4 wires in the plug. Haven't found a relay for it, no relay marked in the pdc for any fan except the aux fan.

PatHenry

Is there a random red/light green wire nearby? It appears that's the missing wire (though I'm color deficient, so I can't be trusted on colors. )

dave1123

Okay, I think I found the missing ground wire. It goes to the mode switch and the mode switch grounds thru G108. SO the plug C201 only has 4 wires that go from the fan switch to the resistor and the 5th contact on the fan switch goes behind the panel to the mode switch. The blower relay is in the junction block.

I just realized I posted the diagram for my 2000 XJ and you have a 94, correct? They should still be the same wiring, just color codes and connector numbers are probably different.

MonacaYankee

JeepWoman

The fuse is good, it was blowing out till I changed out the dragging blower motor. Hasn't blown since, but still only working on high. Wires are attached with shielded terminals on the switch now.