No heat

[dripley]

The heater has been getting a bit slow changing from heat to ac the past month or so. So today, 55 and raining out it decides it is staying in the AC mode. I figure maybe the stepper is going dont know that it might internal to the box. I put the heater treater part in it some years back so I dont think thats the problem. Any good way check that motor to see if its bad without pulling it?

[Haggar]

Dave,

 

No not easily.  I attached the wiring to the blend motor. (and put a snip here) You could check that the voltage varies on the yellow/orange relative to ground as you turn the knob from cold to hot.  If it changes then you know that the command is being given.  Checking for the response is a bit harder.....   You could measure resistance from the Dark blue wire to the black light green wire to see if there is still a servo motor in between.... (if it were an open circuit you would know it is dead.)

 

 

2001 FSM Ram 8W-42-2.pdf

[Tractorman]

The above test would be a good test, but before I did that test I would turn the key to the "run" position and rotate the temperature control knob and carefully listen with my ear close to the blend door actuator motor.  If I could hear the motor operate (or try to operate), then I would think the problem would be a mechanical one downstream of the motor.  If I couldn't hear the motor operate (or try to operate), then I would follow up with @Haggar's advice.

 

I definitely want to know your fix because my Heater Treater part has been in use for 5 years now.

 

- John

[dripley]

Hopefully I will have some time to try that. That is if I can my deaf ear close enough to the motor to listen. My HT part has been in for 7.5 years and my ears have been bad for longer than that. 

[Bojon]

I had an issue last year where my actuator would occasionally work, or not. I was able to pull it out and identify a few bad solders. Used a soldering iron to reflow the joint, been working flawlessly since.