69 Heater Box - Vacuum Controlled Door

[Pat K.]

Thanks,

Pat

[Lee S.]

Re: 69 Heater Box - Vacuum Controlled Door

Thanks,

Pat

[Pat K.]

Re: 69 Heater Box - Vacuum Controlled Door

Lee,

When vacuum is applied to the respective side of the actuator, the door moves in the direction as you would expect, but it just doesn't fully close all the way. I'll take a look at the book, AIM, and service manual again. But based on what I've seen with the fit of this system, I would not be surprised if it doesn't close all the way.

Maybe someone else will weigh in on this subject?

Thanks,

Pat

[John H.]

Re: 69 Heater Box - Vacuum Controlled Door

Thanks,

Pat

Pat -

The air gap between the bottom of the defroster duct and the top outlet on the heater box is standard GM design practice, to avoid noise/vibration from being transferred from the heater box to the defroster duct, and then amplified by the instrument panel top surface (like the flexible bellows between the top of your furnace and the sheet metal plenum feeding the ductwork).

[Lee S.]

Re: 69 Heater Box - Vacuum Controlled Door

Pat -

The air gap between the bottom of the defroster duct and the top outlet on the heater box is standard GM design practice, to avoid noise/vibration from being transferred from the heater box to the defroster duct, and then amplified by the instrument panel top surface (like the flexible bellows between the top of your furnace and the sheet metal plenum feeding the ductwork).

John -

I have been trying to help Pat out with his instrument panel HVAC system. He saw an old posting of mine and reached out for guidance. I have helped him with a few things. Right now, his biggest question is that the mode door on the heater box (AC) doesn't close all of the way.

My '74 has been back together for a few years and I don't recall how this looked. Is the door supposed to close all the way? Thanks, he'll appreciate it.

Lee