How to test the heater Blower? Or Relay fuses? - Jeep Wrangler Forum

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Old 01-09-2011, 10:14 AM
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How to test the heater Blower? Or Relay fuses?

My heater fan won't come on. (it's cold and heat would be nice)
Anyone know the best trouble shooting method or order I should go in to find the problem before I take apart the whole heater housing to get to the blower motor and replace it.

I'd hate to replace the blower motor only to find out it's the switch or something else.

The fuse is fine. I took apart the dash and got to the heater control in the dash. I cleaned the fan switch... but have no way of knowing how to test the dang thing... or if it's getting power to the blower. Any help how to test the switch would be great. I have also read there is relay fuses. I found two next to the battery... are those the relays for the heater? Should I replace those first? Or is there a way to test if they are working?

Also, under the dash is a white "switch" looking thing just hanging down. It has a little push button on one side and a black and green hard tube coming off it. Is that part of the heating system?

Thanks in advance.
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Old 01-09-2011, 09:16 PM   #2
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Do you know how to use a multi-meter ?
if so give me a call and i will walk ya thru testing .

if not a easy way is to run a piece of wire from a fuse box lug with 12 volts or from the battery pos. and unplug your fan motor and hook up the 12 volts directly.
if the motor is good it will run and then you will know it is in the switch or elsewhere .

Scott Howard
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Old 01-13-2011, 02:33 PM
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Okay, Finally got a day above 20 to start working on the heater. Ran direct wire from battery positive to blower fan plug. It kicked right on. So, I have eliminated the blower being bad.

I am guessing it is the switch on the heater control unit now. However, there is still one wire connection under the dash behind the heater that I wonder if it connects to the heating system and is causing it not to work?
Picture is here
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