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1996 GMC Sonoma Heater doesn, t heatup

Tiny
GMCHELP
  • MEMBER
  • 1996 GMC SONOMA
  • 6 CYL
  • 2WD
  • MANUAL
  • 13,100 MILES
I started with a problem of that the heater stopped putting out heat. I first checked the the heater hoses. And they were not hot, the upper rad hose was and the lower hose was hot. There was very little flow through the rad.
I have checked and replaced the thermostat. That didn't help.
I then replaced the water pump, then I started to get a little more flow, but the heater hoses still are not getting hot.
Do you have any Ideas. I would be thankful for any help.
Ray.
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Sunday, December 23rd, 2007 AT 11:02 PM

3 Replies

Tiny
SERVICE WRITER
  • MECHANIC
  • 9,123 POSTS
Three thoughts on this.

Back flush the heater core.

Check the heater control valve for a restriction.

Check the quick disconnect nipple at the manifold for restriction.
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Sunday, December 23rd, 2007 AT 11:18 PM
Tiny
GMCHELP
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Sunday, December 23rd, 2007 AT 11:51 PM
Tiny
SERVICE WRITER
  • MECHANIC
  • 9,123 POSTS
Was that an echo?
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Sunday, December 23rd, 2007 AT 11:59 PM

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