HVAC Servo's Not Working

[Kevin L]

As I continue to debug the car I found that the servos controlling the heat, demist mix, and foot/face mix do not work, they simply do not move. The recirc does work, I can see the servo move but I identified all the other servos but those do not move. Interesting the previous owner apparently only wanted cold since the heater valve is rubber-banded closed.

Any idea what to check? I checked behind the retrostats but they appear fine. The fuse is okay and I wiggled the servo leads but nothing... I know, wiggling is not the most scientific method but I do not have my tools to check for voltage.

One other oddity... Is it normal for the alternator redlight to stay on the entire time driving? In the manual it states this is only on when the car is on but the engine is off or if the alternator is malfunctioning.

Thanks for the continued assistance.

Kevin

[Rick Muck- Mark IV]

You need to check for voltage to the servos, otherwise the "wiggle test" is as scientific as you can get. Harbor Freight has a multimeter for less than $10.00 that is basic junk, but works for this type of diagnosis.

The alternator lamp shou;ld not be on when the car is running at a reasonable RPM (1500 and up) Possibly a ground issue or a improper wiring job.

Forward me your email and I will send over the SPF factory update bulletins for your car.