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'95 Jimmy 4X4 - Heater fan is Intermittent


DelCoch
11-13-2007, 06:13 PM
'95 Jimmy 4X4, 115K - The heater fan will sometimes stop running. At first it only did in on high, but now it will do it on all speeds. I'm thing it might be the heater fan relay, but before I start throwing parts at it I was wondering if anyone else has encountered this problem.

It hasn't stopped working long enough, or at the right time for me to do any trouble shooting while it's dead. It happens mostly when I'm driving down the hwy. Very hard to trouble shoot something when it's working.

MT-2500
11-13-2007, 07:03 PM
Go over wiring plugins and connections.

DelCoch
11-15-2007, 10:04 AM
Good idea - I never thought about that. I'll see what I can find. Thanks.

old_master
11-15-2007, 03:22 PM
Concentrate your efforts on the blower relay, blower motor, blower motor ground, and the connections associated with them. Due to the order they crapped out, it's doubtful that the switch, blower resistor, switch feed circuit, or high blower relay feed circuit are at fault.

Sinful7
11-15-2007, 10:10 PM
In '92, the blower current was passed directly through the switch. My switch got fried, as did the wiring harness and exhibited the exact same symptom.

old_master
11-16-2007, 03:27 PM
Blower current passes through the switch for all speeds except high. All speeds also pass through the relay. All speeds except high, pass through one circuit in the relay, and high speed passes through it's own circuit when the relay is activated by the switch. The common denominator that would cause high speed to fail first, would be after the switch and resistor.

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