I recently replaced my climate controls.

Are those vacumn tubes just plug and play are do you use some sort of goop to get a good seal?

I notice when I have the selector switch set for the heater I hear a air hissing. This goes away when I move the switch to any other setting.
I still get air blowing out the vents.

 

Plug and play. Hissing sounds like a leak. When I replaced the heater core in my 78, I went through and tested all those vacuum actuators and lines before assemblying the duct work.

Air has two settings the MAX and the other (whatever its called). But the difference is that in MAX all outside air is block by the vacuum actuator closing the door to the outside. The other A/C setting permits outside air into the cabin.

When you place the switch at another setting, you are simply selecting another line and vacuum actuator to operate another door whether its defrost, heat or vent.

When you say you replaced your heater controls...what does that mean?

You replaced the switch on the console?
You replaced the Bowden assembly (located on air distribution box)?
Other?

I'm assuming your 77 is like the 78 underneath except the thumbwheel switch. In 78, we have the sliding switch. The Bowden assembly is like an A/B box and connects the console switch vaccum lines to the vaccuum actuators (these operate each flap or door). It's possible to crack one of these lines and not know it. But it sounds like you've narrowed it the A/C switch.

It's a pain I know to remove the console and begin troubleshooting but that would be my recommendation. You should be able to put a vaccum gauge on the A/C line (unless its already disconnected) and test its ability to hold vacuum. If it loses vacuum than the problem is on down the line.

Others may have other suggestions.

 

Thanks for the reply.
You answered my main question about the plug and play. This will greatly help to focus in on the problem area without wondering if I needed to goop it.

I replaced the entire control set on the consol.
http://cgi.ebay.com/ebaymotors/77-78...QQcmdZViewItem

I'm pretty sure the 77 and 78 are identical. No thumbwheel on 77.

It look like I'll have to open it up (once again) and dig a little further into it. I'm gonna have to pick up a vacumn gage one of these days.

With this cold weather and snow/ice it has been difficult to get out and warm the car up properly to see what I am getting for warm air and where it coming from. Actually its been difficult to anything in the garage.

 

As you know by now its plug and play.

When you open it up listen for the hiss. If its coming from the switch its probably defective. In side the switch is a hard rubber spacer...a little bigger then a silver dollar. It has a patern on it made of raised rubber...it is that pattern that directs the vaccum. If there is any play in the casing that contains that spacer it will leak vaccum.

Hopefully it is something simpler....like the plug not being tight enough. there are suppose to to be clips on each side that hold the plug to the switch.

Jim

 

Let me know how you make out. I have the same problem. Also when I change settings I hear a clicking in the relay. Is this normal?

 

The selector switch have been known to be bad. I had the same problem in my 77 with a new switch the vacuum was leaking. New don't mean squat. If you got it from Wilcox let him know they are great people to deal with.