Cannot get hot air to blow, cold air blows great.

[JasonRausch]

I cannot get hot air to blow out of my vents or defrost. Blower works great, a/c works great, but no heat or defrost. Someone had advised me to make sure the coolant was full, that was not the fix. It is getting cold here in St. Louis, does anyone have any ideas?

 

[JasonRausch]

Hey guys, its getting cold in St. Louis. I cannot get my heat to blow hot form my vents or defrost. Had been advised to check the coolant level, this is not the issue. The a/c works great, the blower is blowing air hard, just cannot get any hot air to come out. Does anyone have any ideas? Thank you.

 

[about20ninj45]

remove cable from negative battery terminal for about 15 minutes, then set the controls to heat. This will allow the hvac to try adjust/perform its own calibration. If that doesnt work smell around the inside of our car for a sweet sticky hot smell. This is usually the case with bad heater core, especially if you cant maintain coolant levels in you radiator/reservoir. Your heater core is also responsible for defrost. If your windows fog up or develop a film or there's a wet like stains on the passenger floor, thats another tell tale sign. If none of these seem to fix the issue, then you more than likely have an actuator problem.

 

[NVNJ]

Thermostat or heater core flush. Try the tstat first.

 

[Sparky_69]

Engine coolant coming up to temp?

I had a problem like that with my old Grand Prix, turned out there was air trapped in the heater core, I removed both lines to the heater core, flushed it with a garden hose both ways, bunch of air bubbles came out, worked great after that.