TestPoint

My brother showed up with a '95 Cherokee with the AC/heat fan non operational. Been searching for best part of an hour with no answer. Not familiar with Jeeps . . . Volvo's I know.

Fuse #5, 30a good. Fan doesn't run in high position. Not getting voltage to resistor connector.

Can't figure out how to get to AC/heat control panel to test for switch operation/connector.

First question: how do you get to the switch?

Second question: any shortcuts to solving this.

TestPoint

Second effort.

Fuse 5, 30a good. Removed and reinstalled

Checked the Speed Resistor and found good connections, no heat distortion to the plug and seemingly good resistance values. Put it all back.

Took the switch apart and found one of the connectors loose between the male spade and the rivet to the slide connector. Pinned it tight. Connections through the switch seem correct . . . without a schematic to go by.

Pulled the dash apart and found that the connector to the switch was a little, maybe more than a little, heat distorted. Cut the connector off and soldered female spade clips to the wires for connection to the switch.

Removed the blower motor. Voltage from the switch/resistor is 11.9v with no load. The motor will not turn on this voltage. Possibly drops significantly with winding load but haven't clipped into the wiring to test that.

The motor shaft feel tight but that could be from the permanent magnets. Oiled the shaft bearing exposed with the cage off. No help. Connected the motor to a bench battery and it runs fine.

Suggestions appreciated.

steelybill

Might still be the switch. Can you jump any terminals on the switch to make it run ?
The speed resistor has a little fuse across it, which protects wiring etc, but it should still run on high if the little fuse is open...
On mine, a '94, the climate lever has to be anyplace but off for the fan to work....

TestPoint

Resolved this issue(s) today and would like to thank all that commented on this thread. Here is the schematic on the fan system:



The fuse was still intact but badly corroded including inside the plastic body. The contact tabs had been cleaned in this photo but were corroded also.



The next issue was the switch associated with the Heat Mode Selector Switch. The connector tabs were corroded and the plastic body was distorted indicating high resistance and current at this point. This device was the core of the problems as the internal slide was burned to the point of not conducting. The electrical switch part of this assembly is only available as a complete assembly for about $200. I would hesitate buying an used one for all the current issues of this obviously under engineered system.

The switch can be opened and cleaned, which I did with a Dremel wire brush. Cleaned the grease with brake cleaner and used silicone grease to put it back together.



The next contacts on the schematic is the Blower Switch. The connector here also was severely distorted this time too much to save. I cut the connector off and soldered individual spade connectors to the wires and cleaned the switch contacts WELL before reassembly. I also disassembled the switch and cleaned the contacts internally.



The resistor unit did not appear to be heat distorted at all and the resistances were of such small values that were beyond the effective range of my HF VOM.

With that everything worked but I am not sure for how long. Jeep should be ashamed of the design of this system. What I did today would have involved about $400 in parts and that or more in labor.