What's the difference on the A/C when it's on MAX and NORM? I took apart the 3rd gen controls to get an idea of how I'm going to make my 4th gen controls work. I can't find any difference between the A/C switch when it's on MAX and when it's just on NORM.

 

Vacuum is applied to the orange line and switches the door from drawing outside air (from the cowl) to recirculating the inside air.
The 4thgen selector will do the same thing as the 3rd.
The only thing that is different in operation is bi-level. The heat/defrost vent is a 1-way solenoid as to where the 4thgen has a 2-way (no vacuum defaults it to half open).

 

Ok, that makes sense.

Another question. When the selector is on defrost, why is there power applied to the Light Green wire?

 

The A/C works in the obvious position and also, bi-level (I think.. I'd have to check again) and defrost.

 

Why does the A/C kick on for Defrost? I didn't know it did. For the regular A/C switches (max, norm and bi-lev) power is applied to LIGHT GREEN from the blower switch, and DARK GREEN recieves ground. But on defrost only LIGHT GREEN gets power, DARK GREEN is out of the loop,

 

A/C comes on with defrost to dry the air which clears the window faster. Using the heater only takes ages for me.