Weak vacuum on white hose

[mp3deviant721]

I'm trying to diagnose an a/c issue where the a/c goes to defrost when I accelerate. I noticed when going through the vaccum lines that my outside/recirculate door motor does not work. The door is not open when the knob is on Max A/C. I pulled off the vacuum line and the vacuum seems pretty weak when the line is off. I compared it to vaccum at the switch and there is a difference in vaccum strength. Could a leak on that part of the vacuum circuit cause enough of a vacuum drop during acceleration to make the system default to defrost?

 

[mp3deviant721]

I already figured it out. The vacuum line for the water heater control valve was unplugged causing the leak. Now the recirculating door opens and the a/c does not go to defrost anymore. It still does go to defrost on near wide open throttle, but I guess that is to be expected.


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[rtg143]

Glad to hear you found the major leak. There must be a smaller one for it to still do that unless you're really on it hard for a long time. Thanks for the update.

 

[mp3deviant721]

Another update, I was using the a/c from work to home and when I got home, I found coolant leaking from the heater control valve. That was probably why it was unplugged in the first place. So I am going to try a new heater control valve to see if it will maybe completely solve the a/c issue too.


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