A/C system blowing hot air.
 

Recently had the AC system serviced & was nice & cold, but when I went to raise the temp a few degrees today it went hot & stayed there. Turned it on and off several times & it came back to normal. Thought I would check it out again tonight. It was nice & cold but when I raised the temp again it went hot and stayed there. This is heater air hot, not just lack of A/C or outside air temp.This is the automatic HVAC system. Is there a temperature control door that might be stuck?

Does the temperature display ever blink?

No, the display does not blink. You can move the temp shown on the display all the way up & down and the fan speed works, but I am getting maximum heat all the time & we have a few hot days coming up!

Well, you're stuck because the 96 does not have on-board diagnostics. The dealer is the only one who can to the diagnostics.

But we can check a few things.

When you are receiving hot air, does the compressor turn? What happens if you dial the temperature back down to 60 degrees?

Mine did the same thing except the service thing. One day I went to turn the temp down and next thing I know it's 90 in my car, hot air was coming out with it off as well. I shut it off and hit auto a few times I think it was 5 times but it came back haven't had a issue since. Might have just been a coincidence though.

The compressor is running, but all I get is full hot regardless of where the temp is set. I wonder if it's and actuator that controls the hot/cold mixture.
Just like you said Jr Faust, I hit the auto, off, & A/C buttons several times and it finally seemed to come back to normal earlier, and I should have left it alone when it was cold, but when I had another look at it tonight I adjusted the temp upwards and now itis stuck on max hot again.

On my '92 SE, I know that you can actually *see* the heater core actuator in action once the glove box is completely removed (an easy job).

Perhaps that's a place to start looking.

Agreed; sounds like you have some sort of problem with a mixing door in the ductwork possibly getting hung up on something...

Hey Fuddy. The temperature numbers were blinking for a while. What does this mean?
If this means that I will need a new control panel unit I will be thrilled because I will get one from the wreckers & just plug it in.
I have spent hours under the dash and cannot get to the air mix door. It is supposed to be controled by an electric motor, but seem impossible to get to without removing the whole dash. I think the air bag system makes the whole thing more complicated.
Thanks for your input guys.

It's possible that the passenger's airbag makes access to the airmix actuator a bit harder than on my car, that only has the driver's airbag.

However, you may want to try to remove that lower plastic panel on the passenger's side, just above the passenger's feet, if you haven't already. Then you might be able to reach the actuator from below with your hand.

Take a look at this photo, I took it while working on my car. The heater core is that radiator on the right, normally there's a black plastic case that covers it, with the airmix motor mounted right on top of it. That metal rod just above the heater core, controls the airmix door. The motor rotates an arm that connects to that rod. You might be able to reach it from below.

My car is a '92, so yours may be a little bit different, but I think the general design is the same. Here are the links (you may need to open a new browser window and copy&paste them):

http://www.geocities.com/uri14979/100_0647.JPG
http://www.geocities.com/uri14979/100_0645.JPG

Hope this helps, let us know how it goes.

The blinking number means that you have a stored diagnostic code that will tell you exactly what is wrong with your system. Only the dealer can get it out for you.

Thanks a lot for the pictures uri, i can see what you are talking about but I am afraid I would have to remove the whole dash to get to it. I can't reach it from below and all I see in the glove box is the plastic assembly that carries the air to the glove box vents and the air bag directly above it.
Thanks fuddy I might have to go to the dealer. The only other thing I might try is to see if a wreckers will let me swap control panels.
Can you tell me if you have a phone number for ZZP. I want to get a sc coupler and I can't get a response by e-mail and their 1-877 number doesnt' work from Canada. Or can I get a coupler anywhere else? Thanks

Okay, wait a minute here...

First of all, don't waste your time swapping control panels; that would be like shooting the messenger. The blinking temperature display (it will blink at you for two minutes after startup, then light constantly after that) means that one or more error codes have been stored. If you get the codes out, that will give you a large clue about what's wrong. If the mixing door is hung up (which it sounds like it is), it may tell you that. There's certainly no point in ripping out half the dash without first extracting the error code(s).

I think there's a TechInfo article on how to do that; follow the link at the top of this screen... Wait, here you go:

http://www.bonnevilleclub.com/techinfo/?article=45

So if you haven't got your error code(s) out yet, do that before you do anything else.

Whoops, I see FuddyDuddy's note about how that procedure may not work on 1996 models... What the heck, try it and see.

In any event, get the codes out however you need to _first_; that's what they're there for.

Yes, someone tried that on the 95-99 models with no success. I don't think the problem is the control head. The stored code will tell you the problem.

Problem solved!!. Did a little more troubleshooting on my own and found the actuator motor that controls the air mix door was faulty. Uri sent a couple of good pictures of the dash apart showing where it was located but is is impossible to reach on cars with the air bag. I could see only two solutions. Remove the whole dash as Uri did or cut through the air duct behind the glove box. I cut through the air duct just to the right of the left outlet, removed it, and glued it back in place when I finished. This makes the job quite easy. Now if I can just figure out how those little black boxes fit back up under there I will have everything back in place.
Thanks for the help guys.

It's good to hear you got it solved :-)

btw, did you ever get my reply to your email from a week ago or so?