Defrost Problems

[Chris929]

The heater in my 85 works really good except for the fact that I can't switch between floor, mix, panel, and defrost. When the heater is on it is always on all of them. I can't get it to be just defrost or just one of the others for that matter. I know it's not a cable problem because I can shut it off and control the AC.

I really don't know what is wrong any help would be greatly appreciated.

 

[Broncobill78]

The heater in my 85 works really good except for the fact that I can't switch between floor, mix, panel, and defrost. When the heater is on it is always on all of them. I can't get it to be just defrost or just one of the others for that matter. I know it's not a cable problem because I can shut it off and control the AC.
I really don't know what is wrong any help would be greatly appreciated.

You have two different types of environment controls. Some use a cable to to change between positions and others use vacuum to open/close the stuff that needs to open & close. Being an 85 I'd guess that you probably have a vacuum leak somewhere in the system and the mix door isn't opening or closing as a result. I'd start bycarefully removing the heat/AC panel and taking a look to see if maybe a hose has come off, or (more likely) split and you've lost your control vacuum. I t can be a hassle to track down but the good news is that it'll be a cheap fix. It's just the time involved in tracking down the leak and seeing just where you've lost your vacuum cap or split a hose. One of the other guys probably has a diagram of the vacuum routing for this panel or you can just search the archives because I'm sure I've seen similar posts before and I know that the vacuum routing has been posted up as a reply at *least* once before so it's here on the site somewhere. If it's not vacuum (and if i recall correctly it's the blend door that's vacuum operated) then it's probably simple like the end of the cable to the heat/AC selector has lost the retaining capon the end and come off the slide. If that's the case you can get replacement cable-locks from NAPA or if you're in a bind just secure it in the control with a set of needlenose.

 

[snowman74]

I've had this problem recently. Inside the engine well, on the passenger side, up on the top of the heater box is some kind of actuator that switches the door from open to closed between the defrost and the vent. A vacuum tube that looks very much like a piece of 10 or 12 gauge wire comes out of a bundle of wires through the firewall. I think it is white...not sure. Anyway, it goes over to this control lever on the top of the heater box. That particular piece of tubing is split/cracked/broken somewhere, and you just have to chase it through the firewall to find the leak. I was lucky, as mine was broken right at the lever on top of the heater box. See the picture. It's the part with the tubing going to it. I used a piece of rubber hose with an inside diameter just big enough to splice the two pieces together, works great. Good luck.

Snowman

Happy Thanksgiving Y'all.

 

[miksamak8716]

I've had this problem recently. Inside the engine well, on the passenger side, up on the top of the heater box is some kind of actuator that switches the door from open to closed between the defrost and the vent. A vacuum tube that looks very much like a piece of 10 or 12 gauge wire comes out of a bundle of wires through the firewall. I think it is white...not sure. Anyway, it goes over to this control lever on the top of the heater box. That particular piece of tubing is split/cracked/broken somewhere, and you just have to chase it through the firewall to find the leak. I was lucky, as mine was broken right at the lever on top of the heater box. See the picture. It's the part with the tubing going to it. I used a piece of rubber hose with an inside diameter just big enough to splice the two pieces together, works great. Good luck.Snowman

Happy Thanksgiving Y'all.

happy thanksgiving ........ im not to keen on your problem but just be thankful you have heat in your ride