The hush panel is the carpeted cover that attaches under the dash. I've removed mine but haven't really torn past that yet.

I received a PDF detailing heater core r&r but it's at work. I'll forward it because it probably will help.

I've thought mine works intermittently and want to verify that. But I haven't caught a time where it was working and I could stop, pull the engine compartment "relay" (forgot the name of the part) and look to see what the door's doing.

I'm also going to rip out the dummy air bump which might provide a better view of the "problem".

 

I think you have a different problem. The one we're talking about pertains to the temp of the air -- NOT THE FAN SPEED! SunCr can probably confirm, but the blower module (or main controller) sounds like the culprit to me. (Unless the fan itself it bad)!

Read the link I posted two posts back. Don't take out the wrong screws or you'll be bitchin'.... That post explains why!

BTW: I re-read my link. Jet-Jocky has the PDF and he's the one who reference a "dirty head unit edge connector". Don't know what it is, but I'm guessing it's a ground connector for the cover of the main controller. Sounds like the type of thing that could cause intermittent problems.....

 

Yes the problem is the door will not operate properly. I looked in there and the door looks like it wants to close or open for heat but it will not.A/C works fine but no heat. The lights are flashing and the code was fault dorr I beleive

 

If you have a door code, that's generally the motor. Position of the door is returned, electronically, to the Programmer so it knows it's position and if it doesn't respond, the trouble code is set. If the clip connecting it to the linkage was broken, the motor still works and there isn't any code. The link that was posted appears to be for the motor. The Programmer is a different part and it's about $600 for the '96. That's why it's important to make a good diagnosis of the problem; otherwise, you can put a much of money into it and still not fix it.

 

Well thats not good because I can open the door manualy and get heat but if you try to turn the heat down to areund 75 to 80 it will operate close. It just will not open back up on its own

 

Voltage is getting to it one direction, but not the other. Voltage is sent to one side of the motor with the other being ground. That moves it one direction. Voltage is reversed to move it the other way. Voltages are monitored by the Programmer and this way it not only knows that it's moved, but how far it's moved too (based on how long the voltage was applied). If you have the code, usually it's the motor, but it might also be the wiring. You need to check voltages: Positive/Negative in one direction at 60. Voltages reversed on the wires at 90. They are usually Tan/Black and Yellow, but check the PDF you got to verify.

 

I'd like to talk about the blower module a little more....

Because it sits on the top of the evaporator case, it gets pretty darn hot. Normally, that's not good on electronics. For that reason, I'm thinking that module would be prone to failure. Depending on the location (configuration) of the mixing door, motor, and linkage, they might also be included in the "hot zone".

In my case, I think the main controller is operating correctly because the fan speeds up, slows down, switches devices, switched vents, etc... Because the controller speeds up and slows down the fan, I wonder why an outboard component would be required (e.g., the blower module)! I'm guessing the functions of that module may be worthwhile knowing....

 

My door does a number of fun things. Ok, here goes...if you unplug the battery and the door is stuck on to 90 position, right after you plug the battery back in, the door immediately goes back to the 60 position. If you then set the controls to 90, it usually takes it 20 seconds to start moving the door to the 90 position. When I watch the door, when it gets to the midpoint, it'll kind of look like it catches, but keeps moving. When it closes on the 90 degree point, the door will then move back and forth repeatdly like maybe 1/8th of an inch. Then if you set the controls back to 60, the door will go to the 60 point, chill for about 30 seconds, then on it's own go to the midway point, then go back to 60. So in the cabin, the air is cold the gets warm then cold then warm This is really gonna start sucking in the summer time down here in Orlando if I don't get this thing fixed!

 

When you remove power from the system that takes away it's memory. To get it back, the Programmer will cycle the door from fully closed to fully open - that way it knows how long it needs voltage in either direction. Your's sounds like a Programmer fault - at 60 or 90, it ignores the input from the temp sensors and defaults to full cold or full hot. Anything in between, and the door (and blower for that matter) is positioned based on sensor input. The only other way it could be moving would be a short to voltage, though that should blow a fuse and it would probably fry the Programmer (since it's providing both voltage and ground).

 

I just took the blower module off and looked down to see if the door was working and it was. I put the temp to 90 and it went all the way over. I put it on 60 and it went allthe way to the other side.

The problem I have is NO fan speed. I'm buying the blower motor module tomorrow from acdelco and hope this cures the problem.

Can I put a test light on the module now to see if it works? How do you do this? Can you test it without taking the 3 screws out?

 

Well this interesting. I mentioned in the previous post with having trouble with the module. Well I just got back from a 30 trip and since taking the module out removing the 3 screws to look down at the door I noticed after driving a mile or two the air kicked on.

It works great when the fan speed is set to 5 wheather it's 60 or 90. I read a thread where a guy was talking about jiggle the wires around the module to see if it helps. By the fan not responding well on 10 tells me she/module is about to go out. So should I keep it for a while or go buy a brand new one for $120? Also, when it's in park or at a stop light the fan speed/air doesn't respond well. Oh well glad I found the source.

 

I'm not sure about your "source" and I don't understand what the blower module (top of evaporator case does).

Sounds like you're saying the unit works if a manual temp is selected -- but does not on "auto". That would sound as though the main controller in the dash is going out (assuming that's where the auto circuit resides).

Also, my blower has always taken a couple of minutes to start blowing -- even when it worked fine. I suspect that's normal operation where it's going thru a start-up cycle before "deciding what it needs to do".

P.S. Tell me more about your "AC/Delco Store"?!?!?

 

No, my air works on auto and manual just not very good when the fan speed is set to 10. I'm supposed to buy the blower module or blower motor which ever it's called at a bumper to bumper store that sells acdelco parts.

I don't know why the air started blowing all the sudden. All I did was take the 3 screws off and looked down to see the door moving back and forth. I put the module back in tighten the 3 screws and the air half-azz works. Scroll down to post 13 and you'll see the pic and the part I'm talking about.

http://forums.corvetteforum.com/show...post1553509008

 

Thought you had some special store in your town!

That's the module I thought you were talking about. I'd leave the screws loose and check to see what's going on for a couple of days. This is also the part that seems to get really hot. Yeah, it has a big-azz heat sink, but why not mount it somewhere else?

Anyway, if it started working by pulling it, you gotta suspect the wiring harness/plug don't you? Since the evaporator case is plastic, the screws don't provide a ground.

Still wish someone would say what this bugger does!

 

I didn't take the wiring harness apart. That was too intimadating to do at the time. I'll just ask Larry tomorrow. (That's really his name) I bought a test light at walmart tonight and I couldn't figure that out either. I got it to work on the fuse panel but when I tried to test the module it wouldn't light up.

 

I think all we really need is an individual out there with a service manual that could walk us through the process. I know for a fact that it has step by step instructions on replacing the programmer or actuator that deals w/ the climate control. With those things being 160 a pop for the 96's, the Haynes manual is going to have to do for now!!

 

"Still wish someone would say what this bugger does"

It's the Blower Module. Through '89 it provides a ground for the compressor clutch and controls Blower Speed. For '90 and above, it only controls Blower Speed. The Blower signal comes in on the Brown Wire. About 2.5 volts at "1"; 6 or so volts at "10". Output is Purple (or whatever color is hot at the Blower). "1" should have an output of 4 volts; "10", 12 volts. If the Blower Speed is wrong, troubleshoot the voltages first. If the voltages are correct, it's probably leaking air somewhere. Duct work is sealed with foam and that deterioates with age. Drop the passenger's hush panel and if you have air blowing on the floor, you need to take apart the dash and seal it back up (duct tape works as well as anything).

There is a cooling tube from the blower housing to the motor. Make sure it's hooked up and not allowing air to blow into the engine compartment. Feel for air all around the Evaporator Housing, especially where it splits, underneath it, and where the lines enter and exit. If you can feel air, seal it up with some window ribbon sealer (a sticky, clay like substance easily molded and impervious to water).

All Years monitor actual Blower Voltage (Speed). The output signal is spliced and returned to the Control Panel (through '89) or the Programmer ('90 and up). That return voltage is protected by a 5 amp fuse (on the Firewall through '89); in the fuse box ('90 and up). Should the fuse open, the Blower will default to max speed and may run with the ignition off. If you have these symptoms, check the 5 amp fuse.

Blower Motors can draw a lot of amps - 25 if they're worn. That creates heat and is why the Module is in the air stream and has a large heat sink. Blower wiring is usually 16 gage - marginal for a high draw. Check the terminals at the Blower Motor for discoloration. If there, remove the terminals from the weatherpak connector and solder them to the wires. That should stop the voltage drop and keep the blower at max speed when requested.

 

Thanks for the explaination on the blower module! Very comprehensive....

Also, here is the link to the electronic pdf provided by Agent86 (Dan) in my previous thread.

Hope that helps!

 

From this, I'd say brosain and I need to look elsewhere. Whereas slicked25 may need to replace this part.

Agree SunCr?

P.S. If the door changed with this removed (on brosain's car), I would guess the pressure required to open/close the door had lowered (i.e., air pressure pushing AGAINST that action).

 

It would be helpful to stick to a single topic or problem. Some of you guys have different Years and there was a major design change in 1990 so the PDF isn't going to help anyone with that Year or newer.

Technically, removing the Blower Module shouldn't have any effect on temp door operation. A temp door that's flopping around (with or without the speed of the blower) usually has a linkage problem, and absent a trouble code, that's where I'd look.