Topic: 1978 TA's fan constantly blows hot air

[tj455]

I have the selection set to OFF and the temperture all the way to cool.  If the fan did not run all the time it probably wouldn't be a issue but it can get a little warm.  Anyone have any solutions or expierenced the same problem?

I've had this car since 1978 and the fan has ran all the time.  I always wondered if that was intentional or if something was wrong with it.

Thanks for the help.

[ta78w72]

The fan is suppose to run at the low level all the time, unless you switch to a higher level.  Where exactly is the hot air flowing from?  Do your hear a door open and close when you move the top lever?

[Rick]

Yeah, that was part of GM's "astro-ventilation" that was introduced in the 70s.  Air circulated all the time, though the cabin and out the vents on the rear of the door sills.  How much is it blowing?  A little or a lot?  Does the fan control make any difference?  It should increase with each step of the switch.

[tj455]

The air is coming from the vent behind the console on the floor.  When I move the top lever from the OFF position I do hear a door closing.

The fan switch works fine when the desired option is selected on the top lever.

[Rick]

It sounds like it's working like it's supposed to, then.  A low blower speed all the time, which increases incrementally when you notch the speed control up to the next notch -- normal operation.

[ta78w72]

My memory failed me.  The lever that controls the cold/hot is the bottom lever.  When you move that lever you should hear a door open or close.  If you hear that, the door is working properly and you're probably leaking hot air from the door.  The doors had a piece of foam around the edge to seal off the air flow.  That foam breaks down after a number of years and allows hot air to pass (I once turned on my heater and a bunch of foam shot all over the inside of the car).  Try putting the top selector on vent.  You should get fresh air then.

The other thing that it could be is heat from the floorpans.  Is your floor insulated?  Cause those floors can get really hot.

The always running fan was a government regulation.  It's to prevent carbon monoxide poisoning.  Sorta in the same vein as the padded dash...wouldn't it be nice to have all metal dashes in these cars? and collapsing steering columns.

[Clint s]

I havve the same problem on mine I ended up first pulling the fuse on hot days and then finally looping the heater hoses to get rid of the heat.  I only drive on nice days anyway.  I have a few heater and venting issues though and also headers dumping off into only mufflers under the car amd that leads to alot of heat through the floors.  I will be getting a new exhaust this year to help with that.

[Rick]

The doors had a piece of foam around the edge to seal off the air flow.  That foam breaks down after a number of years and allows hot air to pass (I once turned on my heater and a bunch of foam shot all over the inside of the car).

Yep, happened to me too...

[tj455]

I too remember some years ago when black to dark gray foam pieces came out of the heater/defrost vents.  I'm also sure it's not the heat from the floorpan.  You can feel the hot air coming through the center floor vent. 

I am currently working on putting in new carpet (Removed: 1st layer was jute padding down on the floorpan with a thin layer of a clay/tar type material on the top side but was all one piece.  The passenger seat and rear floorboard also had a layer of pure white padding, and the carpet had a padding attached that looked like the outside fibers of a coconut that were pressed together.), headliner, and some re-painted plastic panels so I have not put back the right kick panel.  Is that the vent door you're referring too?  What type of foam should I use?

I'm not sure what it did when the Top lever is set to Vent and the Lower moved all the way to cool.  It either put out warm air OR outside air did come through the dash pannel vents and hot air came out of the center console floor vent.  I believe the only way to stop it was to run the AC.

Thanks again for everyone's help.

[ta78w72]

Make sure that the temp cable is adjusted correctly.  Has the heater box been taken out of the car?  I suspect you need to adjust the cable that's on top of the heater box.  You adjust it by setting the cable to max hot.  Then move the lever by hand to the max hot position.  Then attach the cable.  Verify first that the door isn't moving through the entire cycle.

You can do these adjustments with the heater box in the car.  However, if you have A/C, you'll have to remove the ducts as well as the glove box to be able to see what's going on.  You probably will have to remove the console too.

[rkellerjr]

What is recommended to put on the floorboard to help with heat?  I have a heat problem as well and I think it's because my floorboards are getting pretty hot and heating up the cabin.

[ta78w72]

I'm not sure what it's called but it's the aluminum backed stuff.  On the TAC board, I saw that Jason used that stuff in his resto.  The original was jute.  I installed that tar paper stuff....I wouldn't use that again though cause I don't like it and it's not thick enough to help with sound proofing.  I'm big on sound proofing.  I like my cars quiet.

[bad76]

The insulation you are looking for is Dynamat. Summit sells a generic brand that is alot cheaper and works just as well. I did my entire floor board area and up the sides in the back for around $70. The insulation conforms easily to the shape of the floor and I taped the seems with metal tape.

[Chewey]

Sorry to resurrect this thread, but for those who had the seal on the temp selector door fail, what did you do to replace it? I can't find anything in a catalog that matches a description I think fits the part. Thanks

[Wallington]

If that is the problem and you have it apart then a used door is usually good to swap. I have three heater boxes that I combined for a good one here in Australia and all had good rubber seals/surrounds and many of these have been sitting in the open for years. Otherwise there is also a few other sponge rubber seals that go around wall dividers and possibly also where the rubber door seal flap presses against, use that sticky peel-back sponge rubber strip you can get in various profiles, you want want that springs back after squeezing it so always forms a seal for where it is pushed into and stuck.