A/C and Heater problems
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 834
Likes: 1
From: Keller Texas
A/C and Heater problems
I have a 96 with a LT4 under the hood. I am having problems with the heater controler! It is electronic and I have removed it and cleaned all of the little terminals but still no heat. How do you pull the trouble codes? I know that I am having problems with the door operating correctly but I need the trouble code! Thanks
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Absent a flashing LED in the Control Panel, it probably doesn't have a trouble code. Verify door operation by removing the Blower Module on the Evaporator Housing and looking inside. Door should move while cycling the controls between 60 and 90. If it does, the core is probably plugged up so you can try flushing it out. If it doesn't the linkage may be broken or the Control Panel and/or Programmer is bad. One communicates with other via serial data lines which are monitored by the CCM. Best to troubleshoot with a Tech 2 that will send HVAC signals through the CCM to the Programmer. If it all works, the Control Panel is faulty. If not, you ohm out the Data Lines and if good, replace the Programmer. Bottom line is to get the best price you can for diagnostics at a Dealer or a/c shop and let them spend the 5 minutes it takes to diagnose it for you.
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 834
Likes: 1
From: Keller Texas
Yes I did remove the blower Module and the door looks like it trys to move but dont. I can manualy open the door and get heat in the car. If I drop the temp down to around 80 it will close and not open until I manualy open it.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Pull the passenger's side hush panel and whatever else is in the way to access the motor mounted on the heater plenum. It's connected to the door linkage with a plastic clip (and generally you have to remove the motor to get a good look at the linkage). If the clip is broken, it may give you the symptoms described. You can also try to observe the linkage as you operate the controls or at least listen to whether or not the motor is running. If the linkage is intact, then the motor may be bad or the Programmer isn't sending the signals. You can troubleshoot the voltage inputs to the motor - one side should have voltage and the other a ground at 60; reversed at 90. If you got the voltages, the motor should be replaced. If not, it's either the Programmer or the Control Panel.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Forgot to mention that if you disconnect the motor with the battery connected that usually sends everything a bit haywire. Disconnect and reconnect the battery to reset Programmer memory and then the hit the Auto Button. Motor should move from fully close to fully open and then cycle to wherever the controls are set. This allows the Programmer to learn the door position electronically. While this is going on, the Blower probably won't work and the compressor may not engage. Procedure can take a couple of minutes, but once it's done, everything should work again.
Advanced
Joined: Mar 2005
Posts: 71
Likes: 0
From: Orlando Florida
I had the same problem with my 96. It stored a trouble code "01" and would only blow out warm, but not hot air. I picked it up from the shop (surprise surprise) on an unrelated repair and asked my mechanic about it. He showed me the plate that sits next to the transmission dipstick that has a couple things plugged into it (sorry for the ghetto explanation). He said that after taking that off that I would be able to see the door that controls the hot and cold air that enters the cabin. I went home, took it off, and saw that there was a piece of foam gasket material that came off from somewhere and was causing the door to not operate properly. After clearing it out of there with a long screwdriver, it now works perfectly! Those are the repairs I love, the ones that are free! Just my two cents. 
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Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
You removed the Blower Module. Unfortunately, that foam piece may have come from the Evaporator. From the Factory, there's a foam filter on the other side from what you were seeing. When the Evaporator leaks, compressor oil destroys it and you often end up with bits of foam blowing through the vents. The other possibile place it might have come from is the duct work which is sealed with foam. That isn't quite as expensive (or as necessary) to replace as a leaking evaporator, but if enough of it falls apart, air flow will drop as a lot of the air will be blown through the open joints and inside of the dash. To be safe, I'd get it leaked checked. Doesn't cost much (if anything) to have someone stick an electronic detector in the vents.
Advanced
Joined: Mar 2005
Posts: 71
Likes: 0
From: Orlando Florida
Sounds good. It wasn't like a huge chunk of foam, but rather sort of a long skinny piece that looked like it was wrapped around the lower part of the door (make sense?). Oh well. When that blower module with the big heat sinks was uninstalled, that thing got freakin hot! What is the reason that thing has to have so much current running through it?
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Because the blower, particularly at full speed, needs about about 25 amps, particularly if it's worn. The input to the module is quite a bit less. It pumps that up for the proper output. Do inspect the wiring at the blower motor. Most of the terminals are only crimped which can create a voltage drop/more heat and the wiring is pretty much at it's limit. If they are discolored, remove the terminals from the weatherpak and solder them to the wires.
Advanced
Joined: Mar 2005
Posts: 71
Likes: 0
From: Orlando Florida
Well, I thought I solved the problem with clearing out the foam, but now the door is trippin' again. Yesterday it was stuck on hot, even though you would put it on 60. So I disconnected the battery so the programmer could relearn the door position, and that worked at first. Now if it's on 60, it'll be ok, then all the sudden after 15 seconds or so the door will move by itself to the halfway point, then go back 
Now i've searched this forum up and down, but can anyone tell me how to fix this problem? I'm pretty sure it's not the T-fitting under the passenger fuel injector cover or the programmer itself. The code is "temp door motor circuit fault", so where is this "motor circuit" and how do I get to it to replace it?
Now i've searched this forum up and down, but can anyone tell me how to fix this problem? I'm pretty sure it's not the T-fitting under the passenger fuel injector cover or the programmer itself. The code is "temp door motor circuit fault", so where is this "motor circuit" and how do I get to it to replace it?
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 834
Likes: 1
From: Keller Texas
Originally Posted by brosain
Well, I thought I solved the problem with clearing out the foam, but now the door is trippin' again. Yesterday it was stuck on hot, even though you would put it on 60. So I disconnected the battery so the programmer could relearn the door position, and that worked at first. Now if it's on 60, it'll be ok, then all the sudden after 15 seconds or so the door will move by itself to the halfway point, then go back Now i've searched this forum up and down, but can anyone tell me how to fix this problem? I'm pretty sure it's not the T-fitting under the passenger fuel injector cover or the programmer itself. The code is "temp door motor circuit fault", so where is this "motor circuit" and how do I get to it to replace it?
Now i've searched this forum up and down, but can anyone tell me how to fix this problem? I'm pretty sure it's not the T-fitting under the passenger fuel injector cover or the programmer itself. The code is "temp door motor circuit fault", so where is this "motor circuit" and how do I get to it to replace it?
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Still don't know of anyway to diagnose correctly without a bidirectional scanner. Absent a troublecode, either the control panel or programmer needs to be replaced, more likely the programmer.
Advanced
Joined: Mar 2005
Posts: 71
Likes: 0
From: Orlando Florida
Hey Red, didn't mean to steal your thread there! I've found an actuator out there that deals with the temperature control: http://artscorvetteparts.com/part_de...4-e47ee4e95711
This might be the answer to our problem, but I have no idea where this thing is. Any ideas?
This might be the answer to our problem, but I have no idea where this thing is. Any ideas?
Race Director
Joined: Nov 2003
Posts: 12,220
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Originally Posted by brosain
Well, I thought I solved the problem with clearing out the foam, but now the door is trippin' again. Yesterday it was stuck on hot, even though you would put it on 60. So I disconnected the battery so the programmer could relearn the door position, and that worked at first. Now if it's on 60, it'll be ok, then all the sudden after 15 seconds or so the door will move by itself to the halfway point, then go back Now i've searched this forum up and down, but can anyone tell me how to fix this problem? I'm pretty sure it's not the T-fitting under the passenger fuel injector cover or the programmer itself. The code is "temp door motor circuit fault", so where is this "motor circuit" and how do I get to it to replace it?
Now i've searched this forum up and down, but can anyone tell me how to fix this problem? I'm pretty sure it's not the T-fitting under the passenger fuel injector cover or the programmer itself. The code is "temp door motor circuit fault", so where is this "motor circuit" and how do I get to it to replace it?gp
Advanced
Joined: Mar 2005
Posts: 71
Likes: 0
From: Orlando Florida
That's funny you say that because I had the controller out of the dash today. After coming to the conclusion that my Haynes manual is good for nothing when it comes to instructions on taking the dash apart, I proceeded in finally getting it apart, removing the controller, and lookin' at the inards. I tried the cleaning the contacts with the eraser head of a pencil trick to see if it was a contact problem. While it didn't fix the problem, it did make the green lights go back to normal, rather than very very dim. Let me know what you find. 
Last edited by brosain; Jan 18, 2006 at 08:13 PM.
Race Director
Joined: Nov 2003
Posts: 12,220
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Here is my recent thread.
A quick skim did not reveal the post I was looking for (though it may be in there and I may have missed it). Try a search on controller and heater....
I think the post had to do with a grounding strap or points of contact on the cover of the controller itself.
Sorry I don't have more time to look right now...
A quick skim did not reveal the post I was looking for (though it may be in there and I may have missed it). Try a search on controller and heater....
I think the post had to do with a grounding strap or points of contact on the cover of the controller itself.
Sorry I don't have more time to look right now...
Advanced
Joined: Mar 2005
Posts: 71
Likes: 0
From: Orlando Florida
Ok, I've read the thread and see that we have similar problems with the door acting like it has a mind of it's own. So in order to get to the motor and clip that could be broken I have to remove the passenger side "hush panel". What is this "hush panel" and how is it removed? Dumb question I know, but i've been examining the floorboard area and have no idea what to take apart. Have you already done this to yours?
Last edited by brosain; Jan 19, 2006 at 12:34 AM.
Burning Brakes
Joined: Nov 2005
Posts: 1,211
Likes: 2
From: Dumas Arkansas
I went to an A/C Delco store today and told them the problem I'm having with the blower module. I told him that when my heater is on 90 and the fan set to 10 it blows like it's on 2. Same situation with the A/C when it’s on 60 and fan set to 10 it blows like it’s on 2. He said I need a new blower module. It cost 94 bucks plus shipping. But after reading this thread I may go take it apart myself and look down it to see if something’s stuck. It's only 3 screws so I guess it couldn't be that hard. Oh I have to pick up the part Friday at noon. I don’t like a whole lot with my 92 from being up to par but I guess you always have to expect the unexpected.