Auto Air Conditioning & Heater Repair: 2000 Blazer heater problem, electric cooling fan, colder the air

Question
My 2000 Blazer (4.3 V-6)heater is blowing cold air. When the temp is around 50 or warmer outside, it blows very hot air out of the vents, but the colder it gets outside the colder the air temp in the heater gets. Have checked the hoses going into the heater core, both are hot to the touch though somewhat less when its colder outside) and the control motor is operating the damper door. Temp gage is reading around 190-200 degrees. I'm lost! Any help would be great!

Answer
1. Normal engine temp should be 220 degrees. Check thermostat.

2. Check electric cooling fan for coming ON to soon.

3. Are you POSITIVE that the damper door is fully OPEN and HOW did you determine that it IS fully open ?.


here is an old trick that I still use today. Run the engine up to normal operating temp and set the controls for FULL HEAT. take a blanket and cover the front end pf the grill area so no air can get pulled thru the radiator and while CAREFULLY watching the temp gage to make sure you do NOT exceed 3/4 on the gage see if the air in the cab starts to get HOTTER.


Let me knwo.


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