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10-19-2020, 01:51 AM | #1 |
Registered User
Join Date: Jun 2017
Location: San Antonio, Texas
Posts: 156
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74 C10 Blower Motor all On or all OFF
My 74 C10 with factory air has a problem with the blower.
With the fan on low the blower is off but when set to any other speed it runs wide open. Is this a known or common problem? The speed selector feels normal so I'm thinking there might be a relay between the switch and motor. I can pull and test the switch. Just thought I'd ask first.
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Repairing and driving old trucks is an analog experience. No computers or sensors and they can be fixed with basic hand tools |
10-19-2020, 02:50 AM | #2 |
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Join Date: Mar 2020
Location: The Woodlands,Tx
Posts: 558
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Re: 74 C10 Blower Motor all On or all OFF
there's a blower motor speed resistor in the engine compartment bolted to the ac evaporator cover. that's where i would start. when they go bad it acts like what you are describing.
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10-19-2020, 11:32 PM | #3 |
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Join Date: May 2013
Location: Post Falls, ID
Posts: 884
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Re: 74 C10 Blower Motor all On or all OFF
I just fixed the blower on my '73 Jimmy by cleaning the contacts on the resistor with a wire brush and adding Di-electric grease to the connections.
Then I took the dash apart and hosed out the heater switch with electronics cleaner. works perfect now; high-medium-low (no off)
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10-20-2020, 06:00 AM | #4 |
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Join Date: Jun 2017
Location: San Antonio, Texas
Posts: 156
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Re: 74 C10 Blower Motor all On or all OFF
Perfect!
Thank you guys for the tips. I'll get on it ASAP
__________________
Repairing and driving old trucks is an analog experience. No computers or sensors and they can be fixed with basic hand tools |
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