Heater blower? problems

[superpsychocow]

Heres my problem. The heater blows constantly as far as i can tell. I have climate control, and no matter what temp or fanspeed i set the heater always blows as hot as it can. any suggestions?

[superpsychocow]

all of your great help has led me to believe that i was mistaken when i thought it was the heater blower. my new hunch is that it is the 'trap door'- as haynes puts it- between the heater box and the passenger compartment. Does anybody know where this is? or how to fix it? this manual doesn't say anything more about the door that i can find.

[randman1]

More than likely, you have a problem with your Air Mix Door Actuator. If you have the electronic climate control, the temp should be blinking to indicate a problem. I found out recently that the manual climate control also has a similar actuator. Unfortunately in my case they are not interchangable.

If this in fact your problem, you will need to remove the dash to gain access as it sits on top of the climate control box. I have read some threads here that talk about the replacing without dash removal but it requires the cutting of duct work and metal support brackets. Not what I would recommend. As I type this, my dash is pulled out enough to gain access to the actuator. I too have the same problem.

I don't have any pics of the removal process but can describe the procedure. I'd write a book if I go into great detail so I'll just skim the surface. If you need further explanation, just ask.

1) remove center console if equipped
2) remove floor shifter and mounting plate
3) remove instrument cluster trim and radio/climate/vent trim.
4) remove glove box (not the door, just the black part inside)
5) remove dash trim next to windshield
6) remove 2 10mm bolts and 2 10mm nuts in glove box opening
7) remove 1 10mm bolt at lower right, outside corner of dash (near relay center)
8) remove 1 10mm bolt lower left, outside corner of dash (kinda under the parking brake release)
9) remove 1 10mm nut below headlight switch
10) drop steering column by removing 2 13mm bolts
11) remove 2 10mm bolts above steering column
12) remove 3-4 7mm screws attaching top of dash near windshield
13) rest...
Thar's all the fasteners I can remember. Double check though. There is no need to remove the radio, climate control or instrument cluster.

14) carefully pull dash rearward.

The actuator sits right on top of the big black box thingy. You will see an arm with a threaded portion on one end and a loop on the other. The actuator connects to the loop. Two 7mm screws hold the thing in but I also had to remove a module directly above it to gain access to the inner screw. Remove the 10mm nut that holds the module in place and set module aside. Remove the 2 7mm screws (inner first).

When you replace the actuator, you will have to adjust it. I'll update you on the adjustment procedure once I do mine, hopefully tomorrow.

[superpsychocow]

thanks for your help, i'll have to try to do this soon, its gettin kinda warm... any more help you can give is greatly appreciated

[UNCLECC]

Randman1...
I got a problem like yours..BUT mine was blowing hot air even on A/c..I located the lever arm by removing the glove box, pushed on the arm and I got cold air. OK, thought actuator was bad, but the other day I needed heat so I just turned it on and the door switched over to heat, but now I can't get cold air again, going to push the arm again..

What do you think? Oh, it is auto climate control and its a 1995.

My temp light was blinking at one time, but my problem just happened overnight..it ran fine one day and the very next day, hot air..
Do you know what all controls the door. I see vacuum lines. Any relays, switches, etc?

Oh, should check out the post by JED RULE this forum...he replaced his in about 1 hour...leaving dash intact...looking at mine, it looks like it will work.

Thanks

[superpsychocow]

that seems to be close to whats wrong with mine too, ac gives hot air, off lets air gets pushed through... i'll have to look for those levers, thanks for the help

[randman1]

If you can move the air mix door by hand, then the actuator is your problem. There is a series of toothed gears in there that are plastic or nylon. When the teeth wear down, it prevents the arm from moving. Mine was similar in that it would be OK going one way but not the other.

As far as the installation goes, I've heard three things so far:
1) Remove the dash
2) Cut the vents and steel supports behind the glove box
and very recently...
3) remove the HVAC programmer along with the access door to the heater core

I chose method 1 because I wasn't about to cut anything to change the actuator. To me, it seemed like the cure was worse than the problem. Plus, my interior was partially removed already due to new carpet installation.

When I heard of the third method, I was intrigued. While I had my dash off, I noticed a large crack in the heater box. Since I really didn't have a way of fixing it, I reinstalled the dash. I took a good look at my parts car and here's what I saw:



The yellow line indicates where mine is cracked. It turns out that this is the access "door" for the heater core. Only two 7mm screws hold it on. I removed it with the intent of replacing my broken one but I found two problems: It's nearly impossible to get at the upper screw (but it has been done before) and I have no idea how to remove the rod that extends from the actuator to the ait mix door. It is said that a long screwdriver can be inserted behind the glovebox in order to disconnect the rod. Then there's adjustment after install... I haven't gone any further with it since then so I can't give any further details. If anyone has a factory service manual, perhaps following the instructions for heater core replacement will guide you through the actuator replacement.

Here's a couple more pics that may help with locations and such. Keep in ming that the actuator is not shown in the pics because it was removed prior to taking them.

[pjwlk]

Hey Randman1, thanks for the great photos on the HVAC. I've got a similar problem with my 97 bonneville but I'm not convinced that its the mix door or actuator assembly. My temp display flashes as you described for about 20 seconds. I bought a cheap CTOOLS reader to see if I could get a code but the reader doesn't seem to be working properly. Interestinlgy, when this problem first came up I could only get full hot air. I took the glove box out and gave the mix door arm a poke with a long crew dirver and watche it hunt around a bit before stopping. I can now adjust the temperature to full cold or full hot but now where in between and the temp display still flashes. All other functions seem to work properly (AC has crapped out though). It would seem that perhaps the HVAC controller can't read the internal mix temperature sensor and when I start the car it just defaults to full heat. GM manual says that 15 or 32 degree is considered to be manual mode operation. Prior to this I didn't even know that the heat could come out that hot. (Co-incidental Note: This problem started when I picked up the car from having the transmission changed.)

I wasn't even going to tackle this problem at all until I saw your photos and descriptions here. They make the job look and sound a lot easier. Thanks! The GM service manual goes on and on about disconnecting the air bags and a whole bunch of other stuff that makes the job seem too tough and too expensive to bother with. How far can you get the dash back without disconnecting or playing with the passenger airbag?

Can you post any infomation or photos on the location of the internal sensors? Any help would be very appreciated.

[randman1]

I do not recall disconnecting either airbag although it's pretty easy to do. Disconnect the battery first then disconnect the yellow connectors above each of the hush panels.

The dash can be pulled back enough to do the work with a somewhat reasonable amount of comfort. I found that supporting the dash on the steel support helped a lot. (the shadow of the support I'm referring to can be seen on the door panel above the power lock switch in first pic above. Just look to the left of the shadow and that is the support.)

[ch9493]

Ok, I am getting the same things you all have described. Here is one interesting note tho. I took the car to the GM dealer. In the process of trouble shooting the problem, they cleared the diag. code (flashing display) and recalibrated the HVAC with the scan tool. They said it would need replacing. But when I got it back from the whole diagnostic ordeal TADAA it works fine. and has been working for the last 4 months, without a hitch........until yesterday. I bought new steering wheel radio controls and had to unplug the battery. When I plugged it back in, back to the flashing thing and all heat/all cold no inbetween. Any thoughts on this? Is this a door actuator or more like an internal cabin sensor?

Also, I need to replace my lamp control module, is this hard?

Thanks

ch993

[randman1]

The 93s is the last year for the on-board diagnostics. I was able to "calibrate" mine through the ECC head. Unfortunately, this only lasted minutes. As soon as I adjusted from full hot to full cold, the blinking started again.

If you don't adjust the temp too much, then the calibration may very well last for a while. But when you adjust the temp and the actuator needs to travel past a worn area on the nylon gear, it will probably throw the error code. This is just a theory from my experiences. To be 100% sure, have the dealer read the codes again.

The Adaptive Lamp Module can be seen above the flip-down fuse box on the drivers side. I'm not sure how difficult it is to remove. I removed one while I was stripping a parts car but the dash was alread off.

[ch9493]

Thanks for the info! I will take it into the dealer to have them recalibrate and diag. it again. How much is the door actuator if that is the problem and do you have a gm part number for it?
I found a website http://www.gmpartsdirect.com/ that has all parts at cost. Excellent source.

Also, the Module, the one I need to replace is the one that gives you a lamp monitor indication. Mine goes off even when the lights are off and shows, back up, then head lights, then all out then none out then it just says lamp monitor at the top of the screen. Weird!!! I hope the one you mentioned earlier is it, because I pulled one from a park ave of the same year and the parts cross reference, but the dash had to come out.
The module I need has a huge heat sink on the front.

Thanks for all your help

ch9493

[ch9493]

Just talked to Dealership again, looks like the problem is the
A/C Electrical Temperature Motor Control Sensor
gm part number 16197178

Does anyone know what/where this is located, is it the same as the door actuator.

Anyone remember when you just pushed/pulled a lever for heat and cooling?


Ch9493

[randman1]

Originally Posted by ch9493

Just talked to Dealership again, looks like the problem is the
A/C Electrical Temperature Motor Control Sensor
gm part number 16197178

Does anyone know what/where this is located, is it the same as the door actuator.

Anyone remember when you just pushed/pulled a lever for heat and cooling?


Ch9493

This is the description I get for that part number:

Item Number List Core Price Price
16197178 $185.19 $25.00 $144.45
Hvac - Controls - Automatic temperature controls - Programmer
PROGRAMMER, Pontiac, All 1994

By this description, it is the HVAC programmer (aka climate control computer). Code 40 or 140 (the 1 indicates a history code) indicates the air mix actuator circuit is open, shorted or the actuator needs calibrated. Deeper in the diagnostics, if an open or short is displayed then the remedy is to replace the HVAC programmer. I've helped troubleshoot over a dozen air mix actuator problems this winter but have not run across a faulty programmer. The scantools that the dealers use are pretty fool proof though.The good news is that the programmer will be substantially easier to replace than the actuator. It is located above the passenger's hush panel right next to the PCM. There will be an electrical connection or two and a multi-line vacuum connector.

I would love to have the manual climate control. The ECC does look cool but you are at the mercy of the car for heat/AC. Reminds me of that "Space Odyssey" movie where HAL won't let me be comfy.

I think I understand your lamp monitor problem and it does sound wonky. Before I guve you my thoughts, I need to know what cluster you have. Is your odometer digital and located in the driver's info center or is it analog? I believe in either case the ALM controls it but I just want to be sure. And yes... the ALM does have a heat sink on it.

[ch9493]

That is good news on the programmer. I had this picture of me and the dash sprawled across my garage. As for the dash, it is analog, no speedo in the screen. The only digital it does have is in the HUD. Thanks again!

i had an old Lincoln (1972) that had the auto climate control. You would be cruising along with the ac on in 100 degree heat and the car would decide....ok thats enough, time for some heat.....a ghost in the machine.


Thanks

Ch9493