Hot air from heater when turned off. 93 TS

[knuckle ears]

My heater wafts hot air through the vents when the fan is completely turned off and temp control is set to cool. The fan isn't running but hot air still comes through the vents. It is not hot outside so I should get some outside temps instead of hot. If I turn the temp control up it gets hotter . My a/c dosen't work so can't use that right now.
All controls work okay when I switch to different levels.

Any thoughts out there?

I have taken the cover off the heater core inside the van and can see the dampers moving but can't tell if the temperature damper is closing all the way. I stuck a mirror inside but still can't see it. I will have to undo the heater core mounting screws and move it a bit out of the way so I can see if the damper is obstructed or if it doesn't close enough.

Anyone else have this problem.

[LMP]

1st, the only way to turn the fan COMPLETELY oFF is to push the OFF button at bottom left. Otherwise the fan is ALWAYS on, even at leftmost setting though at a very slow speed. At that low speed, the proximity of the hot core will induce some heat in the plenum even if bypass is actuated and it will be felt as a noticeable increase in temperature of the air.
This being said, it is not impossible that the electric motor that positions the diverter valve has some problem, this has been seen in the past.

[knuckle ears]

Thanks LMP. Toady I undid the screws that holds the heater core in place and looked in behind to see if anything was obstructing the damper from closing. I was really hoping I could find something but nothing found.

I did find that when I turned the temp control to cool, the damper wouldn't shut all the way to blank off the heater core. It would activate the electric motor but only half way. I then proceeded to take the control panel with the " upper, Lower, bilevel switches, out. I realized that the "cool, Warm slide switch was not working. I then unsoldered the switch from the circuit board and took the switch apart. It was very dirty and gunked up. I cleaned it and brushed the points and put it back togetrher. Still didn't work. I suspect the carbon track that the points run against are cracked or worn. I will be going to the wrecker Friday for another one.

Let you know how it works.

[knuckle ears]

Went to the wrecker and picked up the heater/ ac control panel from the dash. Also got the motor that controls the damper at the heater core. The motor is in the storage compartment on the passenger side dash. You have to pull the compartment out and it sits in a hole down below. If you follow the wires that you see in the hole and use a light you will see the motor housing. 2 screws hold it down.

I put it all back together and and everthing works. No more hot air coming through the vents. It would've been okay if it was winter but not summer.