1999 GMC Sierra Heater not kicking out hot air.

  • 1999 GMC SIERRA

Heater problem
1999 GMC Sierra V8 Four Wheel Drive Automatic 194, 00 miles

I have recently been having problems with getting hot air out of my heater vents. I thought it might have been a stuck thermostat, so I replaced it. Still nothing. The coolant level is correct and I think the water pump is operating correctly. It seems to have good circulation and it isn't leaking a bit. The heater core isn't leaking either. The vehicle gets up to the proper operating temp just as before, but still no hot air. I was wondering if I should flush the system, but the anitfreeze looks just fine. I'm a missing something. My next step is the replace the water pump. But I'll probably wait until I know something for sure. Oh, and the temp control is working just fine also. Not, faulty.

Do you
have the same problem?
Thursday, April 10th, 2008 AT 11:34 PM

1 Reply


Could be the heater hose and heater core clogged up/air mix/blend/mode doors not opening or a problem with an actuator or vacuum-

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Friday, April 11th, 2008 AT 1:53 AM

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