Heater on all time

[Christolher]

Back in the winter i changed heater core and evaporator core and i put some insulation around the evaporator to keep air from passing and i think the insulation has the box in a bind or something. The heat is on all the time if u turn the fan on and it fills hot if u stick your hand up to the vents with it off, I was wondering where the vacuum for the flap for ac and if u could see if it will move by hand?

[IBMobile]

I think you might have a blend door problem.  

 

  

[Mopar1973Man]

I just ran across another truck with a heater treated upgrade and the shaft continues to spin endlessly. The blend door has broken away from the shaft and the shaft just spins. I'm going to be forced to pull the entire HVAC case and replace the blend door.

That was the first thing I check on this truck was the stepper motor and if the shaft was metal or plastic. Since the stepper motor still turns this means its a damaged blend door.

 

[Christolher]

Ok i think im not getting power to the motor? I checked the Yellow and orange wire as hot to the ground as black and light green then checked the blue wire as hot as i had a friend turn the heat to cold nob. Am i checking it right? 

 

And can i take a 9 volt battery to the motor to see if it will turn the blend door?

 

Im not sure if i hooked all the wires up when i installed the dash, i remember hooking up the vacuum lines. But my fan works.

 

[IBMobile]

Here is the FSM diagram for the blend door.  Dark blue (DB) wire is battery voltage, yellow/orange (YL/OR) wire is a variable voltage signal from the temp selector and the black/light green (BK/LG) wire is the ground.   I don't think a 9 volt battery is going to power a 12 volt system.  It would be best to see if you have truck battery voltage at the DB wire, changing voltage at the YL/OR wire and ohm test the BK/LG wire for continuity to ground. 

 

 

 

[dripley]

FWIW the heater treater part I installed came with 9v battery to use for indexing the motor. As I remebr it worked quite well.

[Christolher]

Sorry i  posted wrong diagram, but i checked wires again with test light and it had voltage on the blue wire and i jumpered the blue to the yellow and it didnt turn. Im not sure how it works if it was already in that position. I ohmed black to ground and it was good, and ohmed the switch and it was open every way i turned it.

 

Is my switch bad?

[IBMobile]

The A/C heater temperature control is nothing more than a potentiometer so if you're not seeing a variable voltage on the YL/OR wire with an open circuit between pin #3 and #4 then the temperature control is bad. 

[Christolher]

Will i went to junk yard and got a controller and it didnt fix it, i actually got two and took the potentiometer out of the one i didnt put in and ohmed it out and it does nothing. I thought they would ohm out but am i wrong?

[IBMobile]

58 minutes ago, Christolher said:

I thought they would ohm out but am i wrong?

I thought that the ohm resistance would change also.   Does the voltage change on the YL/OR wire when the temp selector is powered up and the knob moved.  

[Christolher]

Will the ground wire had corrosion on it and i got another plug from yard and wired it up, but before i wired it up i checked the wires and yes the voltage changed. But after i wired it up i couldnt get voltage out of plug but it had voltage on the backside of plug, I finally got a tiny piece of solider and put in the plug where the small holes where and it was good. So I may have wasted my time but the wire is a lot better now.

 

The only thing i know is the door must be in a bind so the next thing im going to do is take the actuator off and see if i can turn the door by hand and make sure the actuator is working.