1999 GMC YUKON
243,000 MILES
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ANONYMOUS
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  • 1 POST
I don't have no heat! Change thermostat and heater core it blows cool air when on
Feb 2, 2013 at 8:24 PM
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MERLIN2021
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  • 17,250 POSTS
Can be the heat control valve, if it has one, or the temperature blend door actuator on the plenum.
Feb 2, 2013 at 8:29 PM
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MERLIN2021
  • CERTIFIED EXPERT
  • 17,250 POSTS
Do both heater hoses get hot?
Feb 2, 2013 at 8:29 PM
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