Climate vacuum

[Josh]

Few questions regarding the climate control on a 79.

1) Is the vacuum a "closed loop" system.. Meaning does it retain vacuum when the engine is off? Are any mix of settings suppose to remain vacuum? I have a electric vaccum pump hooked up to test behind a check valve and a canister ball. However, no setting seem to retain vacuum. Is this normal? I'm trying to figure out if I have a vac leak or not.

2) Is the "diverter door" (the door that faces the passengers legs) suppose to fully close when switched to defrost? It's close, but I can still feel air coming out of it. I don't believe there's any adjustment for this, so I assume this may be normal? Or I have a weak diaphragm?


Thanks   

[Wallington]

Somewhat closed but will leak. It requires a constant vacuum source of running engine to operate, with vacuum check valve to maintain it only temporarily when vacuum drops such as under heavy acceleration or steep hills, towing. That's not to say you don't have a severe leak if it doesn't maintain some vacuum.

[firebirdparts]

I think all settings should retain vacuum ideally.  Even off.  I guess the vacuum diagram stickied here would show at any setting what is active if you are hunting a leak.  Curiously, *nothing* is under vacuum in Bi-Lev setting.  You could start with that one.

The diverter door that you see should close in heat and defrost, but because of the way it's made, it wouldn't seal perfectly.