[secondchance]

Originally Posted by QB93Z

The problem with the Heat Blend Door motor is that it is running backwards for a 1994 car. The replacement I installed came out of a 1991 ZR-1. It turns out that in the 1991 and prior HVAC system, the Heater Blend Door Motor mounts on top of the HVAC distribution plenum. In 1992 and later, the motor was moved to the bottom of the plenum, so it is upside down, and operates backward on a 1994 and later car.

The good news is that the motor on the bottom is much easier to access. In a 1991 and earlier model, access to the motor requires disassembly of the entire air distribution plenum. (Visualize Heater Core replacement.)

The failed Heat Blend Door Motor shows evidence of corrosion to the internal parts. I suspect that condensation in the evaporator, (the AC cooler), collects in the floor of the plenum and can enter the motor.

I have ordered a proper replacement motor. To be continued...

Jim

This is some great info! I hope I don't need this knowledge down the road but...