[Triode Pete]

Last month (December - winter in NY), I purchased a 1991 Cab C-4. Unfortunately the Climate Control does not work properly. The symptoms are:
1) Constant heat from driver's side & middle vents. Far right passenger's side vent blows cool air.
2) Round thermostat dial (blue & red dots) does not work.
3) Slide Controls appear not to work.
4) Blower fan 0 to 4 does work properly.
5) Defrost button engages & blasts air through vents not to glass.
6) A/C button turns on (yellow light) but the condenser/compressor appears not to engage -- no change in RPM's, etc.

I have Adrian Streather's 964 book & it appears that the two mixing chamber Servo valves under the front hood may be bad. Any other ideas?

Thanks. This is my 1st post!

Pete