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No heat

Tiny
KRETEMAN
  • MEMBER
  • 1994 GMC C1500
  • V8
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
My heat diplay flashes when I turn it on. All the controls on the heater work except the heat control just flashes. I have ruled out all the usuall suspects so I guess im wondering if the flashing is an indication of a problem im not aware of. Thx
Wednesday, September 8th, 2010 AT 7:02 PM

10 Replies

Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
Yes, the flashing is a telltale for a malfunction in the system usually a temperature blend door actuator. Here is a guide that will help you see how to change it out.

https://www.2carpros.com/articles/replace-blend-door-motor

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Wednesday, September 8th, 2010 AT 7:20 PM
Tiny
KRETEMAN
  • MEMBER
  • 3 POSTS
Thanks for the post, it was the blend door actuator I go a new one for $56.00. I love this site.
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Wednesday, September 8th, 2010 AT 10:31 PM
Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,540 POSTS
  • 1982 GMC C1500
The fan on my heater wont work what things do I need to check for?
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Thursday, November 29th, 2018 AT 6:02 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check your blower relay on firewall and resistor in the heater box near blower. See if those are getting power if they are then they may be bad if not it can be aswitch or blown fuse.
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Thursday, November 29th, 2018 AT 6:02 PM (Merged)
Tiny
JACK354
  • MEMBER
  • 1 POST
  • 1992 GMC C1500
  • 190,000 MILES
Heater quit working, dash control does not light up, do you know what is wrong with it?
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Thursday, November 29th, 2018 AT 6:02 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Start with checking the fuses with a test light. it has to have power to operate the controls

This guide can help as well

https://www.2carpros.com/articles/car-heater-not-working

Roy
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Thursday, November 29th, 2018 AT 6:02 PM (Merged)
Tiny
MIKEY11
  • MEMBER
  • 1 POST
  • 1995 GMC C1500
Hello

I have the following truck above. I have no heat blowing and I did the following already.

Replaced the thermostat
Replaced the coolant temp plug

There is no buildup on the window from the heater coil or any water on the bottom anywhere.

The hoses are hot

Someon told me maybe my whole heater control unit needs replacing becuase when you select the control to either go to vent or bottom it only blows on the defrost part. The 2 butttons for a/c or recircluation do not light up when you press them. However the low, med, high knob works fine but again only blow cold air onto the winshied. Before I goto to the junkyard and waste money does anyone have any ideas.

Thanks for reading this

Mike
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Thursday, November 29th, 2018 AT 6:02 PM (Merged)
Tiny
A-TRAIN
  • MEMBER
  • 6 POSTS
I had an 88 chevy with the same problem. Replaced the heater core, and solved the problem.
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Thursday, November 29th, 2018 AT 6:02 PM (Merged)
Tiny
KRETEMAN
  • MEMBER
  • 3 POSTS
  • 1994 GMC C1500
  • V8
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
When I turn the heater on the display flashes for about 2 or 3 minutes. It also will not let me adjust the temperature control. It just blows cold air. Ive ruled out all the usual suspects. Help please, I dont want to spend a fortune at the dealer.
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Thursday, November 29th, 2018 AT 6:03 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
Your probably going to need the dealer to get the diagnosis confirmed but they had a ton of trouble with the control heads on those. That's the part that's flashing.
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Thursday, November 29th, 2018 AT 6:03 PM (Merged)

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