I was looking at the vacuum line routing for the vent doors, heater control etc. in the manual. Something does not make sense, I see no check valve in the system. For example, the kick panel vent an an A/C car is spring loaded closed with a vacuum actuator to open it. So if you supplied engine vacuum to it (without a check valve), the door would open and close with changes in vacuum, right?
Looking at the HVAC vacuum diagram, I see no check valve. Also, if there is a check valve, the system has to be vented to release vacuum after the check valve. I don't see where that occurs.
EDIT: I found a diagram that shows a check valve for a 1977. Still can't find how the vacuum is released.
Looking at the HVAC vacuum diagram, I see no check valve. Also, if there is a check valve, the system has to be vented to release vacuum after the check valve. I don't see where that occurs.
EDIT: I found a diagram that shows a check valve for a 1977. Still can't find how the vacuum is released.
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