vent ?

[IrvJr]

My a/c vent works most of the time. It seems to stick in the cooler weather, but will eventually open, but when it gets hot and i want to use the a/c it wont come through the vent.
But when it does work it usually takes anywhere from 30 secs to 15 minutes. And when it does open it does with a BANG. Is this vacuum related or is my door sticking in the heater box?

Thanks, Scott

 

[Rickracer]

It's the door sticking

Had the same problem with my 79 Cutlass. I tore the whole dash apart to find and fix it, and only made it a bit better. That's been a long time ago, and I don't remember exactly what the problem was though.

 

[IrvJr]

Does the vacuum open the door? If i put a mighty vac on there will it open the door?

Scott

 

[IrvJr]

Its funny, i went and bought a Mityvac today and as soon as i left Harbor Freight the vent door opened up, or closed, whichever makes it blow thru the vents.

Scott

 

[turbofish38]

Scott,To answer your question all functions but the temperature are vacuum. The temp is cable controled. You might check the vacuum check valve on the firewall,above the coil/module, or the vacuum reservior,the round ball under the left front fender for cracks or leaks.Also check the vacuum selector valve on the control. These are all plastic and like to break causing problems.

 

[Rickracer]

With my Cutlass...

All of the vacuum motors/diaphragms were working fine. Part of the duct work and the blend or mixer door had warped to where they were catching each other. I trimmed both a little, and minimized the problem, but if I was going to do it again, I would probably use a heat gun to re-shape them back to their original configuration. By all means, make sure the vacuum motors are working first though.