so i have a minor problem. i hear a hissing noise coming from the a/c heater controls. as i accelerate it goes away briefly, and as the engine slows it gets louder. i took the dash apart and found the source. its coming from one of the vacuum hoses going into the control that chooses head/feet/ac/defrost. i changed the selector and the hose clusters but to no avail. the selector does work, it changes the head/feet/defrost/ect. but it takes a little while to actually change. doe this mean anything? and how do i stop it? thanks in advance

 

You have to locate the leak and repair the line. If the leak is internal to the HVAC control head, then you will have to replace the control head.

 

i did change all that, the switch and the hose cluster. i wasnt sure if something cause too much pressure that it caused it to leak somewhere...

 

My advice is to get a hand operated vacuum pump like a Mity Vac. You can instantly tell if you have leakdown. I like to pull about 15" hg. You can also pump up the system and watch it work in slow motion depending on how much vacuum you pull. It's great for finding leaks, testing those pesky actuators, etc. You can also hook it up to your engine for troubleshooting all kinds of problems and there's nothing like being able to bleed your brakes by yourself.