blower moto/rfan switch
Discussion in 'Kenworth Forum' started by bluej, Jul 14, 2014.
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Complaint: fan motor inoperative
Possible (common) cause(s): Stuck fan motor relay. Inop. fan motor.
Suggestion: Jump the fan motor with a direct 12v power source and attempt to force the fan motor to work (you could also jump the fan motor relay.) If inop, replace fan motor. If operable, continue electrical diagnositcs. This will include testing the entire circuit for electrical continuity. Check the fuse. Check the relay.
If you are not sure how to test a relay, you could just arbitrarily replace it with a known good relay (like the horn relay for example.) Or, you can learn how to test a relay here: https://www.youtube.com/watch?v=DWmt6gorzUgLast edited: Jul 14, 2014
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replaced relay. try jumping motor next thanks for helping !
Highway Hypnosis Thanks this. -
If that doesn't work the AC has a switch on the high pressure side that communicates with the ECM to energize one relay to the fan. It looks similar to the one on the low pressure side to engage the compressor. The other way to turn the fan on is the temperature switch which also communicates with the ECM to turn the other fan relay on.
The majority of vehicles I've worked on is usually the temp switch. Your symptoms with the AC I'd say the fan switch on the high pressure side. You should be able to unplug it and run a jumper wire across the two contacts and the fan will come on. A few vehicles the switch is naturally closed and just unplugging it will make the fan come on. It's one or the other. -
Highway Hypnosis Thanks this.
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Does the fan work on the high setting? If it does than it could be the blower motor resistor.
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fan does not work on any speed..
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More than likely you will find it to be a motor, just jump 12 volts and ground to it like stated before to verify.
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Be sure to check the wiring harness plug on the back of climate control. I have had to replace that twice on mine.
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thanks!! to all who responded replaced fan. back to being cool
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