1990 Corvette coupe heater control/AC problem

Hi

The control of the auto aircon/heater on my Corvette failed recently (it
just shows '---' on the display and the buttons do nothing). I've followed
the GM manual checking procedures and all of the connections appear to be
fine, I've now replaced the programmer with a new one (part 1572896 on box,
16154551 on the unit itself) this seems to work but the buttons on the
controller in the dashboard all operate the wrong things e.g. temp up makes
the temperature go down, fan up and down change where the air comes out.

Does this mean that I have the wrong programmer?
What is the part no of the correct one?
Are there any comprehensive online parts catalogs that I could use?
Any other suggestions?

I would be very grateful for any help that anyone can give me.

Thanks

Howard (Chandler's Ford, England)