ace_cobra

Hello,
I have finally gotten down to fixing the heat in my 1970, non AC. The heater core was replaced, and the blower runs fine, and I know I have some vacuum hose issues in the interior heater system. I would just like to know what the actuators on the heater box do and why? It will greatly help me diagnose if things work/dont work. Thanks!

hugie82

Your hot to cold wheel operates a flapper from fresh air to heater core air only. That flapper must seal nice or you'll always have hot or cold air getting into the vents.
The selection dial has vac lines going to other diverters sending air to the defroster, main vents and then floor vents for heat. A vac leak in the plastic ball that stores vacuum will cause the defroster to come on when you are giving the car gas going up hill.
The vents should work a few times with the motor off. If you have nothing, there's a leak.

Alan 71

Hi ace,
I'll only add that the change from heat to cold is accomplished by a Bowden cable (the black wheel moves a cable that move the door) not with vacuum direction and actuators as the rest of the functions are.
Regards,
Alan

PeteZO6

Hi Ace,
Here are a couple of diagrams taken from the 1969 Chassis Service Manual.

This is a generic view of the airflow and the doors that control the flow.


This is the Corvette vacuum harness - controlled by the left thumb wheel.

These should get you going.


Pete

7T1vette

This is exactly why DIY owners need to purchase a copy of the Chevrolet Chassis Service Manual and the Assembly Instruction Manual (AIM) for their model year. Then, these answers will be at your finger tips, instead of making a post and waiting for a reply on this Forum.

ace_cobra

Thanks for the help! I have the AIM, but it didn't give me the answers I needed. I figure that what the forums are for.

flyeri

The Chevrolet Chassis Service Manual has been a great tool for me. Between it, the AIM, and a Chilton book I usually wade into a job with a very good idea of what I'm up against. PB Blaster, Liquid Wrench, and a big hammer are also very good tools.