Too much heat!

[David in NC]

My son's 97 4.0 XLT is putting out too much heat. I didn't think it was the blend door problem because we could hear the door moving when we adjusted the control from hot to cold to hot. I changed the heater control valve, but that's not the problem.

The heater control valve opens when the HVAC is turned on. It stays open in all positions and at all heat/cold settings, but if I turn the system to Off, the valve closes. I have it wired shut with wire ties from the bread package.

Where should I look next? Oh, I vote for a sticky on the whole hvac system.

As always, thanks for your help.

 

[David in NC]

I found the sticky, but I'm still not sure if this is the blend door or the vacuum control to the heater control switch.

 

[my98nnj]

If the blend door is indeed moving, then it will cut off the flow of air through your heater core. The heater flow control valve is not what regulates temperature.

That's the blend door's job.

 

[timn8er]

my 96 does the same things. the blend door is on its way out. if you remove the bled doot motor and look in with a mirror you will see a crack in the platic. my 95 suv blend door just broke and it was stuck in the cold air postion. not fun in the dead of winter. I had to pull over and all i had was my fist to break the plastic. I reached in and flipped the door to the hot position. so with that information i knew what to look for in my recently purchased 96. its only a matter of time that it wont work at all.

good luck