Blower works on high

Tiny
SUDSY74
  • MEMBER
  • 1985 CHEVROLET TRUCK
  • V8
  • 4WD
  • AUTOMATIC
  • 10,000 MILES
Hello great web site. I have a 85 chevy scottsdale. When I turn on the switch to operate the heater or a/c it only works on high. I replaced the blower and the switch in the cab. What else would cause the fan to blow only on high and not on low or medium. Thanks for your help scott
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Monday, August 17th, 2009 AT 6:19 PM

15 Replies

Tiny
KEN
  • ADMIN
Hello,

It sounds like the blower motor resistor has gone out but to be sure lets test the system. Here is a blower motor wiring diagram and guide so you can do some testing.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Check to see it losses power here are the diagram (Below)

Please let us know what happens.

Cheers, Ken
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Friday, November 17th, 2017 AT 7:17 PM
Tiny
JESSE RODRIGUEZ
  • MEMBER
  • 1986 CHEVROLET TRUCK
Smells problem
1986 Chevy Truck V8 Two Wheel Drive Automatic

heater won't work. Blower is good replaced blower switch relay what next?
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Friday, November 17th, 2017 AT 7:18 PM (Merged)
Tiny
GP97
  • MEMBER
First q, is it a digital control panel?If it is are you getting power to the control panel(is it lighting up)if the control panel is working check for a bad ground connection, if not check the fuse.I personally recommend the haynes manual for that year, or the haynes elecrical manual this will help you somewhat understand how to check for power. If your desperate for heat, pull the blower relay (high side) I ran a jumper wire(single wire) from the green/white stripe to the brown wire(hot ) this is what I do on my 88 chevy to get heat(hint wait until the engiine warms up a little. When mine does the same thing yours is doing this is what I do for heat. All my relays are good, the blower works, its just my digital control panel does not work. Intermittent problem!
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Friday, November 17th, 2017 AT 7:18 PM (Merged)
Tiny
IRVAFGI
  • MEMBER
  • 1979 CHEVROLET TRUCK
  • 10,000 MILES
What is the wire between the relay and the blower motor on a 1979 chevy c30 w/ac. Looks like a old inline fuse. I have a photo.
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Friday, November 17th, 2017 AT 7:18 PM (Merged)
Tiny
WRENCHTECH
  • EXPERT
Are you going to post the photo?
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Friday, November 17th, 2017 AT 7:18 PM (Merged)
Tiny
IRVAFGI
  • MEMBER
Yes sure am, just wouldn't work earlier.
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Friday, November 17th, 2017 AT 7:18 PM (Merged)
Tiny
IRVAFGI
  • MEMBER
Yes Let me know.
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Friday, November 17th, 2017 AT 7:18 PM (Merged)
Tiny
WRENCHTECH
  • EXPERT
That's a radio noise suppressor.
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Friday, November 17th, 2017 AT 7:18 PM (Merged)
Tiny
IRVAFGI
  • MEMBER
Can I get a second opinion from anyone?
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Friday, November 17th, 2017 AT 7:18 PM (Merged)
Tiny
VALVE6
  • MEMBER
  • 1986 CHEVROLET TRUCK
  • 20,000 MILES
When I started fixing the blower motor, I only had one fan speed.
I replaced all of the components in the blower motor circuit (blower motor, relay, resister, and switch)
Now I have nothing the fuse is good. I can get the blower to work with direct power to the switch all three speeds and a fourth (the off position). I m lost
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Friday, November 17th, 2017 AT 7:18 PM (Merged)
Tiny
WRENCHTECH
  • EXPERT
Sure you can. You can ask them any of your follow up questions too.
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Friday, November 17th, 2017 AT 7:18 PM (Merged)
Tiny
HMAC300
  • EXPERT
Check your fuses according to this chart i've sent there are two fuses for the blower/ac system. Make sure the relay is hooked up correctly.
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Friday, November 17th, 2017 AT 7:18 PM (Merged)
Tiny
IRVAFGI
  • MEMBER
My biggest question is why is it there and how come I continue to look for a replacement but can't find anything that comes close to it. Is it really that old?
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Friday, November 17th, 2017 AT 7:18 PM (Merged)
Tiny
HMAC300
  • EXPERT
Sorry forgot to send. Arrows point to where they are. Also which lead to check.
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+1
Friday, November 17th, 2017 AT 7:18 PM (Merged)
Tiny
WRENCHTECH
  • EXPERT
No, it's probably an aftermarket add on put there to reduce radio interference from the blower motor. It was probably done by someone installing a radio.
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Friday, November 17th, 2017 AT 7:18 PM (Merged)

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