H3 quit blowing hot air - Blower works

[poncho1965]

I did the HVAC calibration. The resister mod was completed years ago. Just no heat. Any quick tips? A forum search suggested a mixing valve actuator?

 

[Korby7]

I’ve had this happen to me from a thermostat failed to open not allowing it to come up to temperature. Cheap and easy fix. I’d start there if you haven’t checked that yet.

 

[poncho1965]

I've replaced the thermostat years ago. That gave a code because it wouldn't come up to temp fast enough. No codes at this time.

 

[the_real_hacksaw]

I've replaced the thermostat years ago. That gave a code because it wouldn't come up to temp fast enough. No codes at this time.

Could still be the stat...


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[3rdH3]

Check your Coolant Level if you haven't already.

 

[poncho1965]

Coolant level is good, temp comes up quickly and does not overheat. Blending door motor operates. What am I overlooking?

 

[poncho1965]

I’ve had this happen to me from a thermostat failed to open not allowing it to come up to temperature. Cheap and easy fix. I’d start there if you haven’t checked that yet.

Are you talking the main engine thermostat, or is there another one exclusive to the heating system?

 

[Happy Hummer]

Starting looking into the blend door, actuator assembly controls. Also, take the time to verify that it is indeed not a plugged up heater core.

 

[poncho1965]

Starting looking into the blend door, actuator assembly controls. Also, take the time to verify that it is indeed not a plugged up heater core.

Yep, was looking at the drivers side, there are three of them. Two worked but one did not. I removed it, and the heat is mysteriously working now. All functions work without this actuator installed. Heat, cold, floor, dash, defrost, you name it. So at this point I'm not sure. It's not the temperature blend door, or the one that diverts the air where you want it. Not sure of its function. ???