Heater stuck on full blast...

[Pack Ratt]

A while back I had my heater going at full for about an hour. After that I couldn't turn the heat down. I've tried tracing the wiring back, and I think I may have found where the wires go. There's a Generic Electronic Module mounted on top of the heater core. I'd suspect this to have been cooked when I was running the heater, but I can't confirm that it connects to the temp control since I'm not reading any change in impedence when I hook a meter up and mess with the temp control. Maybe I just cooked the wiring harness? Is anyone here familiar with the '98 fan and wiring? What does this module really do, and does it connect to the temp selector?

-PKR

 

[NCG8R]

A while back I had my heater going at full for about an hour. After that I couldn't turn the heat down. I've tried tracing the wiring back, and I think I may have found where the wires go. There's a Generic Electronic Module mounted on top of the heater core. I'd suspect this to have been cooked when I was running the heater, but I can't confirm that it connects to the temp control since I'm not reading any change in impedence when I hook a meter up and mess with the temp control. Maybe I just cooked the wiring harness? Is anyone here familiar with the '98 fan and wiring? What does this module really do, and does it connect to the temp selector?

-PKR

My '96 V8 (without climate control) would only blow hot air (fan controls worked fine) except in Max A/C position (since that actually closes the valve that feeds hot water to the core). I physically wired this valve closed to buy some time before having it repaired - if your problem is similar you may want to see what your Ex does in Max A/C mode. You seem to think your problem is more electrical but my problem was fixed by replacing a plastic gear that controls the "damper" (which I think adjusts the amount of hot and ambient/cold air based on temperature dial position). I hope yours is easier/cheaper to fix since this cost me about 10 hours labor to replace a $2.00 part. I was told to NEVER put your dial at either extreme position (turn it to full cold or hot and back it off a little bit) since it puts pressure on the gear. This may be BULL but after this expense you can bet I'm doing it. Good luck!

 

[NIGEL420]

I Had The Same Problem In A 1996 Explorer It Would Either By Hot Or Cold One Or The Other , Theres This Little White Boxing Behind The Dash Board Behind The Glove Box Hooked Up To A Vacuum That Wasnt Working
Fixed The Problem Right Away

 

[Nitrous SSC]

either that or your blend door took a dive.