: Heater/Air Conditioning repair?

04-10-07, 05:40 AM

I have a 72 sedan deville. The heat and air conditioning worked when I purchased the car, but after dismantling the dash to get to the heater core, I have a problem - the heat will come on, and so will the AC, but they dont blow into the cabin of the car properly.

I think my problem might be the operation of the blend door (black plastic box behind the dash on the passenger side of the car). I remember that when I went to put it back together, there was a long metal rod coming out of it about the diameter of a pencil. I have the shop manual, but it didn't really describe how to attach it.

I seem to remember it being some sort of gripping fit (the rod going up through some sort of clamp or cheap screw), but that at the time it really didn't seem like a tight fit at all, and there could have been multiple ways to angle this rod before attaching it back together to the blend door selector apparatus.

Is there a clear, detailed set of instructions on how to connect all of this back together? Especially steps such as how to decide if you should have the blend door open one way or the other before hooking it back up, and then how to make the connection with the screw more secure? This information is greatly needed.

Thank you!

Old Fleetwood
04-10-07, 12:48 PM
There was a whole bunch of posts about that very thing on this board about a month ago.
You may want to take a trip back through the "back issues" and have a look at the posts for "no heat" and subjects like that. A lot of detail was covered.

04-10-07, 05:16 PM
thank you! i'll check it out :)

04-10-07, 06:21 PM
I checked previous posts and believe I found the threads you're referring to.

What I'm after, however, is a more detailed description of how this rod coming out of the blend door connects to the vacuum/motor linkage that opens and closes the door. When I had it all apart I seem to remember a horizontal bar with a screw that tightened onto the rod, and then when this motor or vacuum was activated, the arm would spin the rod, opening the door. This screw didnt actually go through the rod, I dont think. I seem to remember it just pressing up against it and relying on friction or threads which, after 30 years of use, may easily get worn?

Does anyone have pictures of their blend door and the actuating lever that spins the rod and opens the door? Does this system work on vacuum or is it an electric motor that moves the arm? Most importantly, how can I fix this screw/rod connection so that if it's stripped or worn the blend door will still open.

I didn't see any information about this specifically in previous posts and would be very greatful to anyone who can help. Thank you!


04-10-07, 08:09 PM
Mine's newer than yours (1981), but to set mine up you're supposed to set the heater to full heat, wait for it to move the arm all the way, and click it in the arm. After that it says to give it a little tug on the rod (holding the arm the rod connects to) to make sure that the blend door is sealed. Turn it all the way cold to make sure it closes all the way.

Mine's an electric motor... don't know about the earlier ones. That little clip on my car isn't in the greatest shape either, but it still works at the moment.

04-10-07, 08:33 PM
thanks for the instructions... ill definitely be able to use those when i put the thing back together again. but my main problem is that im not sure what sort of connection is supposed to be made between this rod on the blend door and this arm/screw connecting to it. is there some sort of a clip, or does the screw just screw up to and against the rod? i would really like a picture of this setup so that if im missing a piece i can try to make a cheap fix. pictures anyone? please! thanks.