LeSabre Heater Problem

[kilkm]

I've had 2 occasions this winter when the temps drop below zero the heater in my '95 Lesabre will not put out any heat. Engine temp gauge shows normal and no coolant leaks. Happened once in December, then the heater worked fine until 2 days ago when we had another cold snap with temps down to -4. The first time I drove the car for over a hundred miles and heater never did get warm. Next day when temps rose above zero, heater worked fine. Same thing happened yesterday, no heat at -4 but when the temp rose to 7 above later that afternoon heater worked fine. Any ideas what could be causing this and what I can do about it?

[Guest Straight eight]

Sounds to me like another 2 quarts of anti-freeze will do the trick. Seems like she's freezin up

[NTX5467]

If the temp gauge is not showing hotter than it normally does, that part of the system should be working "as designed". As it seems to be somewhat sproadic, you might get the various door actuators in the heater/air conditioning module under the instrument panel checked to see that they are operating correctly, plus the instrument panel controls too. Some of those actuators are probably electrically operated now, rather than cable or vacuum.

Next time this happens, rather than punch the "Heat" or "Defrost" button for heat, see if you can get some heat by using the "Bi-Level A/C", normal "A/C" function, or "Outside Air" with the heat lever in the "hot" position (in each case). IF you can get heat out of the system like that, then it's probably an actuator issue--with the actuators not responding to the commands from the control module or no commands coming from the control module. Yes, you can get heat with the a/c turned on or in the outside air mode, and it'll come out the normal instrument panel and floor outlets just like the cool air would if the Heat lever was in the "no heat" position.

See how that works . . .

NTX5467

[JohnD1956]

Several things you might check.

Look to see if there is a bleeder valve on top of the thermostat housing. If so, when the engine is warmed up , open the bleeder a turn or two till it spits out antifreeze then shut the valve. This will let any air out of the top of the engine.

If you do have air at the top of the engine, you should investigate why. Did you recently have the water pump replaced? If so maybe it just wasn't filled right ( ie this bleeder procedure). However, if you have not had any work done recently, I would take the vehicle to a garage and ask them to do a pressure test. There are several places that can be a problem and I don't want to panic you but driving the car with air at the top of the motor is not a good idea with these alloy engines.

Another thing to check is if the temperature control is working right. For some reason my 93 Regal with dual heat controls is malfunctioning this winter on one side only. When I slide the heat control to full heat, I can watch the electric motor first turn to open that door, then back off a bit, resulting in reduced heater output. But back off the slide control by one notch, and the heater works fine. It's too cold to dig into that just now since I have heat at this setting. I would recommend you warm the car up and experiment with this.

And yes, these are electric motors. There is the possibility that the cold is affecting them at those negative ambient temperatures. However I suspect it may be that the seals on the internal air doors are freezing to the ducts because of dirt or dust, and then opening once the car is shut off and heat from the heater core soaks the system thus thawing things out.

For this you may want to have someone raise the car on a lift and check the drains for the A/C. Perhaps this is plugged causing a little flood inside the system.

If none of that works, park it till the weather warms for sure. No point in getting the flu because of a car heater.

Good Luck

[Guest norb]

The same thing happened to my Buick .It was a door under the dash ,part of the automatic system that was not opening.On my car you take the hush panel off to get at it. It is not easy to work on.Not cheap either.

[kilkm]

Thanks everyone for their input. I remembered that I did replace the A/C-Heater control head this summer. It shorted out and when I priced one at the Buick Garage they wanted around $700 for it. Couldn't see spending that much on my work car with over 100k on it so I got one at the salvage yard for $40 and put it in. I swear that whole unit only weighed a couple of ounces, can't believe what they charge for these electronic components. Anyway, could be that used unit causing the problem, but I suspect what someone else said, it's a door under the dash not opening, I'll look into it, thanks for your help guys.

[JohnD1956]

Norb, what did you have to do to fix the door? When I took off that panel I cringed looking up there. It looks like the easiest way to fix this is to pull out the entire dash board. Of course in my case I think it is the head unit alone because I can see the motor turn the door all the way over and then back off.

I do have a spare unit I got from a junkyard. I just need to put new light bulbs in it and then I can swap them out. Of course changing these light bulbs is a real PIA. But it is do-able.

JD

[Guest norb]

Dont pull the dash off. Reach up in there & feel a door then turn the heat on & off & try to move the door by hand to see if heat come out.