67 BB Factory Air Heater Shutoff Vacuum Switch

[Stephen G.]

On the 67 BB AC car vacuum comes from the intake to the vacuum switch on the top of the heater box and then back out to the water shutoff valve.

My switch seems to be bad and the new one I just got from Long Island seems bad as well. It seems to switch vacuum on and off to the port for the shutoff valve but it leaks vacuum.

I have not been able to start the engine yet and have been checking the system with a vacuum pump and Mighty Vac. You can hear the vacuum leak. I would think with the switch off and vacuum applied to the input port you should be able to hold a vacuum.

Any input/help appreciated.


Steve

[Wayne W.]

Re: 67 BB Factory Air Heater Shutoff Vacuum Switch

They actually have a controlled leak built in, so it might work when the engine is running and you have full and continuous vacuum. Look closely and you will see the very small hole.

I dont care much for the original switch. I use the 70s plastic switch.

[Don H.]

Re: 67 BB Factory Air Heater Shutoff Vacuum Switch

I had trouble with mine and finally eliminated it. I plug the vacuum into the coolant shut off valve when I need heat and unplug for AC (plugging the hose and outlet when unplugged). This would not work for a PV but other than that very effective. Good luck, Don H.

[Stephen G.]

Re: 67 BB Factory Air Heater Shutoff Vacuum Switch

Wayne

Can you give me info on the 70's switch you use.

Thanks

Steve

[Larry M.]

Re: 67 BB Factory Air Heater Shutoff Vacuum Switch

They actually have a controlled leak built in, so it might work when the engine is running and you have full and continuous vacuum. Look closely and you will see the very small hole.

I dont care much for the original switch. I use the 70s plastic switch.

A small air bleed is necessary to allow the hot water valve to depressure and close when you do not need the hot water to the heater

Larry