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Should a heater vacuum switch hold vacuum at the "off" pos?

Started by DaddyDeVille, February 25, 2018, 08:39:40 PM

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DaddyDeVille

67 DeVille  : QQ

Does anyone know if the heater/climate control vacuum switch hold vacuum at the "Off" position?  I would assume so, otherwise you have a vacuum leak when off.

Thoughts?
Thanks
C
1 Old car (The Green Devil~le) (Lots of gas)
1 New Truck (Not quite lots of gas, but still a lot of gas)
1 New Car (no gas)
1 Newish Bike (Some gas)
1 Old bike (Some more gas)

https://chuckdidit.wordpress.com/
https://www.instagram.com/mightneedoil/

cadillactim

Are you referring to the vacuum master switch on the firewall (four vacuum lines going into top of it)? If so, no, it should not be holding vacuum when the dash control is in OFF. Vacuum is shut off in that position, and any vacuum actuators will bleed off any vacuum in them, thus allowing the master switch to lose any vacuum in it. If master switch is holding vacuum, system (and blower) will stay ON.

Tim
Tim Groves

DaddyDeVille

I'm referring to the heater control switch under the dash.  Vacuum line comes into the switch and then the heater control levers direct vacuum to operate the air flow doors on the floor or for defrost. 

When its set to Off, I would expect that the switch should hold the vacuum, other wise it would be a vauum leak.  Am I thinking about this right?  Or am I not understanding it correct?

Thanks!
1 Old car (The Green Devil~le) (Lots of gas)
1 New Truck (Not quite lots of gas, but still a lot of gas)
1 New Car (no gas)
1 Newish Bike (Some gas)
1 Old bike (Some more gas)

https://chuckdidit.wordpress.com/
https://www.instagram.com/mightneedoil/

cadillactim

There is vacuum going into one of the ports of the valve from the engine manifold. In OFF, the vacuum is is sealed off. Vacuum cannot leave that port unless it is leaking. In other dash settings vacuum is routed from that port to different ports on that valve (not all the ports at the same time).

Tim
Tim Groves

DaddyDeVille

Thank you Tim!  That's what I thought; but wanted to make sure :)
1 Old car (The Green Devil~le) (Lots of gas)
1 New Truck (Not quite lots of gas, but still a lot of gas)
1 New Car (no gas)
1 Newish Bike (Some gas)
1 Old bike (Some more gas)

https://chuckdidit.wordpress.com/
https://www.instagram.com/mightneedoil/