HVAC Control Module Question

Automotive
1

My Focus had the blend door actuator replaced earlier this year, and after I got it back, things got wonky with the directional controls. Setting it to front vents only had some air coming up at the windshield, setting it to feet only had it come out from the front and windshield vents, etc.
I’ve seen a few videos where the HVAC control module is disconnected and replaced, but in those videos, the cause for replacement is things like getting no cold air despite the actual ac system being fine (no freon leaks, blower and compressor are fine). Would the fix for my directional control issue be just to swap out with a fresh control module as well?

2

Sounds to me like the module doesn’t know the position of the actuator and the two are out of sync.

3

So far from what I’ve seen, it doesn’t seem able to be re-calibrated or adjusted, but I wonder if that’s possible Whole thing is just a electronic module that gets plugged into some wires, so I imagine it would take skills I don’t have to figure out what it’s spitting out and what it should be spitting out.

4

How about turning it to a state, unplugging the module or the actuator and then setting it to that state, then plugging it back in?

Is it in defrost mode? Unplug actuator, rotate knob to defrost, plug it back in.

5

I had a similar issue with the AC in my pickup. It would only blow cold on the passenger side. The drivers side was always heat. I cycled the connectors (unplugged and replugged) a few times and it came back to life and would blow cold on command on both sides - for a while. I then unplugged the connectors and:

  • cleaned them with alcohol and a q-tip stripped of most of it’s cotton
  • burnished with wood toothpicks until they came out clean
  • used DeoxIT D100L on a clean toothpick to lightly coat the contacts

and it’s worked for a year (knock wood.)

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6

It could be as simple as they didn’t install your blend door actuator correctly. I.e. it was supposed to be plugged in at a certain setting and now it’s off.

The Autel scan tool should be able to read the states that the HVAC control module is commanding. I don’t think the vent setting are typically in there, you’d have to check the wiring diagram for your car. If you go to your service manual in prodemand I bet it maps out the control system for the HVAC and how it tells the blend door to select the right setting.

1 Like
7

And, I believe that Pro Demand is a service that we’ve got a license for or own.

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