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How to fix a 1996-2000 HVAC control module

Repair the module instead of replacing it.

How to fix a 1996-2000 HVAC control module

Postby Richard_Nixon [OP] » May 14 2012, 4:01am

If you have the following problems, this fix will probably work for you.
- Vent control knob does not work
- Vent door actuator turns, but only a few degrees
- A/C Button does not work
- Recirculation button does not work
- Fan speed and temp knobs work fine

The problem is a bad transistor on the control module.
The transistor is the one located next to the vent control potentiometer, under the plastic post . (The difficult one to get to, not the easy one mounted at the edge of the board)
Replace the transistor with a MPSA56 (PNP) transistor (or similar) from a local RadioShack or electronics store.
The easiest way to replace the transistor is to mount it to the soldered side of the board, instead of trying to cram it back into the tight space between the potentiometer and the plastic post.
Make sure you mount the transistor in the right direction after flipping it to the other side of the board.

Plug the module back in and youre good to go.

I read about this somewhere else and thought I might share, if this is a repost, don't mind me.
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