2nd Gen Non-Engine/Transmission Another heater problem!

[Bpostel]

Hey guys, looking for some help. When I turn the heater to say defrost it put's out warm air not hot. I can live with that for now. But the problem is when I turn the knob to combine the defrost and floor heater, the floor heater works ok but the defrost blows hardly nothing and it's alot cooler than the floor heat. What is wrong?

 

[B.G. Smith]

When you go to defrost mode the air conditioner compressor comes on to dehumidify the air, thus the cooler air up there. As for the low heat, it could be a blend door problem or maybe the thermostat in the engine or restrictions in the water flow to the heater core?? bg

 

[Bpostel]

But shoudn't both areas put out heat and not just one. As long as I select one area of heat it's not bad. But when you combine them, heat on your feet and the windshield, nothing comes out of the defrost no matter what speed you turn the fan on.

 

[B.G. Smith]

On the 99 you have eight positions on the A/C/heat switch, Off, Max A/c, Panel A/C, Bi-Level A/C, Panel, Floor, Floor/Defrost and Defrost. The A/C is off in the Panel, Floor and Off positions. Sounds like you might have a blend door problem, there have been reports on here of same. bg