My heat and air control slider doesn't change directions [floor-dash-defrost] when I slide controller. It just comes out at dash vents. I moved slider to heat this morning, the heat came out of dash vents, but none of the heat came out of floor vents.

I need information on how to fix this, and hopefully pictures showing what/how to do this.

I have a Haynes book, but it doesn't show me what I need to know.

It seems that I've heard that this controller has vacuum lines, but I don't know where/how to find them to make sure they are ok and hooked up.

Please help.
slowboy

 

The vacuum lines are connected to the back of the temp control unit. Hopefully, you'll find one of the lines is just disconnected but you may also have a falut in the diaphram of the vacuum control valve.

 

Thank-you for your reply.
If it's not the vacuum lines, where would this "vacuum control valve" be located? And is this repairable, or replaceable?

 

The most common problem of this is that the vacuum diaphragm retainer is broken. Most GM cars of this era use them. they break all the time. All parts stores have replacements and they are easy to fix. It's located on the back of the climate control panel. where the colored vacuum lines are connected.

 

The control valves are located under the dash. First pull the climate control unit and inspect the plastic lines, make sure they're connected and that the unit's select control is intact. If all appears to be okay then trace the plastic vacuum tubes to the control valves.