Installing 1993 air mix door actuator into 1990

[ThunderVette]

Hi Everyone,
Installed 1993 airconditioner air mix door actuator into 1990 (car is with RPO C68 - Electronic A/C), now a/c cannot calibrate itself, actuator is permanently in move - rotating forward and back all the time, - seems there's difference in 1993 vs 1990 actuator harnesses, but I don't have any clue on connectors layouts...
Experts help is appreciated, thanks in advance.

 

[boomdriver]

Thats got an electric servo?
I thought all the air doors were vac operated. If it is vac, then the signal comes from the programmer that responds to control head signals. The programmer is above the gas pedal on the firewall.

 

[vetteoz]

Thats got an electric servo?
I thought all the air doors were vac operated.

On Elec Air (C68 ) the blend door that controls air temp has a stepper motor that constantly moves to blend hot air through the heater core and fresh air ( or cold air from the evap core ) to achieve the programmed temp . The door should self calibrate ; key on Vac only controls vent position(s) and the coolant shutoff valve ( in some years )

 

[boomdriver]

Thanks, I was unaware of the electrical element in the door management. I always assumed the door was either open or closed...I "get" why it would need to vary position constantly. If this one seems lost, is it from a bad inside air temp sensor possibly?
Or just a different stepper motor?

 

[ThunderVette]

Just different stepper motor is...

Thanks Guys,
answering boomdriver's question - yes, it's different stepper motor now installed, - it has different wire harness - so I am puzzled which wires now do what: with motor feed wires its clear which are those, question is which is +5 Volts reference, which is potentimeter responce voltage and which one is ground... If one could give a layout and/or schematics clue - would appreciate. The wire colors are: black, light blue, grey, yellow and blue...
Thanks

 

[vetteoz]

The wire colors are: black, light blue, grey, yellow and blue...

From the '90 and '92 bibles

Position feedback pot .
Black ;ground
Red ;5V reference ( yellow/black on 92, might be same as '93)
Light blue ; mix valve feedback to programmer ( same colors both years)

Stepper motor
Yellow terminal 5
Black/ tan terminal 6 on '90

Gray/ black and light green/ black on '92