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Just wanted to make a post to discuss some theories I have on the issue. So the fan blows hot all the time regardless of temperature selection on dial, what vents the air comes from, A/C or recirculation on or off. On occasion, if I move temperature dial back and forth about 10 times, I'll get some cooler air from vents. Took a guess on the temperature control valve, connected to heater core, being faulty. No dice on that, valve opens and closes great. I also noticed that with valve connected to actuator cable, while on car, the arm that opens and closes the valve, wouldn't move more than 1/4" or less. Valve moves back and forth much more in hand. With less resistance than new valve I might add.

My theory on what may be causing this issue, is either the potentiometer dial, for the hot/cold adjustment is either worn or dirty, or the actuator servo motor that moves heater control valve cable, is worn, needs lubrication, or is weak..

I ordered a used, pot/dial module from ebay thinking it's the next logical thing to try. Pulling that cable servo motor is going to be a real b*tch if that has to be done..

Thoughts?

 
Rep Power: 222

Sounds like you're on the right track.
maybe try disconnecting the cable at the servo and try operating the cable. Then watch the servo moving back and forth with and without the cable attached

 
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Took pot module apart, found temp dial pot to be grittier and less "clicky" than the other 2. Tried cleaning it with De-Ox-Id, but potentiometer is a sealed unit, not much spray is getting in there. I have a good feeling the switch is the culprit. Like I mentioned in post, if I moved dial back and forth 10 or 20 times, I'd suddenly get the temp to change.. Same idea as a stereo receiver, with a flaky center switch or volume ****. Indicates a faulty pot.. 👊

 
Rep Power: 222

Good on you for actually knowing how to diagnose something 👍 rarely the case anymore

 
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Very few true mechanics left in the world.. Mostly fresh out the textbook parts changers. Everybody just throws out, or shotguns something that wasn't even close to the issue, then charge you $900. Things do need replacing of course, but why buy new when something can be repaired, if it's worth repairing of course. In this situation, replacement parts were inexpensive, and sourcing a correct replacement pot is difficult. I'm sure I could do it, but replacing the climate module seems simpler. 👊👊

 
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Just an update, temperature adjustment potentiometer was the problem. Replacement OE climate control module dials felt much better than old dials, were very, "notchy", like they are supposed to feel. Fresh air coming into car almost feels like the A/C is on! Glad I was able to find the solution.