the topic says it all, im having a serious vacuum leak and i cant find it, but i noticed that all of a sudden my heater vents arent blowing anything out. can someone elaborate to me on this?

 

The various air routing doors are indeed operated by vacuum servo motors. If you don't have any vacuum at all to the control switch, the default is defroster.

The vacuum source is a small hard plastic line that connects to the intake manifold behind the carb. It goes through the firewall with the harnesses above the heater hoses.

How do you know you have a vacuum leak? Can you hear it, or does the engine run weird?

 

Yes the vent doors are controlled by a vac source tapped from the manifold. Im assuming you have a carb thus posting this on the carb board. Behind the carb I guess also on a tbi theres a T connector on the intake that can have 4 connections on it, most have two, the vac source for the climate controll is tapped off of that. The line then goes into the blower motor housing. So if all fails just look for a disconnected line from the heater box or pull the raido out and check for a break/disconnection on the controlls there. If you recently installed a stereo or were farting arond in that area you might haveaccedently disconnected a line.

SSC

 

five7kid, the car runs like crap, it idles really crappy, and is always fluctuating. ssc, i checked my climate controls today and all was well unfortunately. i keep tracing the lines back and nothing, nothing new. im about to take my car to a shop, yikes dont really wanna do that but i havent driven my ride in almost two weeks. any more ideas?

 

I might be able to help as i had that exact symptons - the chiltons says that the temp (cold hot) slide moves a cable to control the flap, but mine has a little circular vac switch and vac hose. The switched side hose goes nowhere and the source hose was disconnected - rough idle (but wasn't too rough) and no air through the vents..

I've temporarily plugged the hose and haven't dug around to find where it goes yet, way to large to be crawling around under there but i also need it fixed as i also have no air coming thru the vents and its so bloody hot here.

I'm going to try and operate each vac motor with a tail off the hard plastic line this weekend and find the vac motor that does this hot/cold door.

when you win can you post what you found.

 

Summertime in Oz, eh? Come to Canada for a while--we'll cool you down. It was -25 Celsius here in Calgary last week.

That wretched little piece of hose coming from behind the carb gets soft after a few years and ends up pinching itself off under pressure. It's a good thing hose is cheap. I have found that the pinch happens close to the carb connection, so maybe you can just snip an inch or two off and be sitting pretty again.