Anyone familiar with GM Electronic Climate Control

[wkilleffer]

Hey everyone,

I've posted a post similar to this on an Oldsmobile-related forum, but it doesn't seem to have alot of traffic. I'm sure there are other forums out there that could be helpful, but I'm missing them somehow.

Not too long ago, I did some work on my 1993 Cutlass Supreme Convertible that got the Electronic Climate Control back into an operational state.

The problem is that the PO removed the actuator motor from the heater blend door actuator arm over the summer and moved the arm to full cold. Well, this was great for summer, but it's colder now. He kept the old part so I would have something for a reference when replacing it.

I ordered the replacement from rockauto.com and installed it yesterday. I dialed the temp up to 90, watched the motor move, then opened the blend door, then put the motor on the arm and fastened it down. That was one of the most PITA jobs I've ever done on a car... The motor appeared to be responding to input from the ECC control panel, so I didn't give it much thought after I was done.

The problem now is that it seems to get stuck on heat. It was cooler last nite, so I dialed in a little heat. When I tried to turn the heat down, nothing happened. It was like it had gone to full-on, boiling hot heat. I even pushed the Cooler button all the way down to 60, and the fans came on full speed and blew nothing but extremely hot heat.

I also tried installing it by unplugging the actuator and adjusting the blend door arm in such a way that it matched the actuator gear cam, put everything back together, and plugged the actuator in last. Then, I started the car. The climate control was off, and I had a fingertip on the actuator. I felt it activate and stop. I waited about a minute, and turned the climate control on. Once again, regardless of temperature setting, the vents blew nothing but hot air.

What have I done, or not done, that was wrong? I know it's installed in the right direction cause it will only fit one way.

Any suggestions would be appreciated, as well as directions to other potentially useful forums.

Thank you,
-Bill

 

[Banjo]

Not real familiar, but here's some info.
Press OUTS TEMP and BI-LEV at the same time to enter the diagnostic mode. Press any mode button to get out.
a 2 digit code is a hard fault, a 3 digit code is an intermittent fault.
00= nothing wrong (At least in the processor's eyes)
01 or 101 in-car air temp sensor short
02-102 in car air temp sensor open
03-103 outside air temp sensor short
04-104 outside air temp sensor open
(one of these sensors may be the problem).
05 or 105 air temp valve motor circuit
09 or 109 serial data line failure
to reset codes pull the ELEC 15-amp fuse in the instrument panel fuse block.
hope this helps.

 

[KSIS]

this sounds like the same system on the newer SAABs with the error codes.

 

[racingenglishcars]

Seems to me that by installing the arm and motor when temperature is set to 90 deg and heat flap full open, you are assuming the two are congruent. This may be incorrect, as you have probably already guessed, however it may not be too far off.

As you said, the actuator is responding. It doesn't look like that is a problem then. It really sounds more like the temperature feedback mechanism isn't working properly. When the output temperature gets hot and the interior warms up, you would expect the actuator to reduce heat. If it isn't moving towards cold, maybe it just doesn't know that the interior is already warm enough.

I don't know anything specific about this system, just general control system knowledge. To maintain the temperature, it must measure the temperature, compare it with a target temperature and send a "error" (deviation) signal to an amplifier which powers the actuator. A couple things can go wrong. Sensor not giving signal, comparator not comparing the temperature signal to the target, amplifier not working, actuator working reverse from that desired.

In the last case I can only describe an imaginary scenario:
It could be that when the interior gets hot, the resulting actuator motion would move for example out. If the flap is made so that when the actuator moves out then temperature gets hotter, then the control system is reversed. It would (in this imaginary case) need reversing so that when the actuator moves out, the flap would move towards the colder direction.

 

[wkilleffer]

Ok, here's what happened:

I started the car this morning and did the diagnostic check as described by Banjo. Got a 00, then a 05. I didn't have the actuator plugged in at the time. The interior got hot pretty fast.

This afternoon, I pulled the 15amp fuse and plugged the actuator in. Then, I replaced the fuse and started the car. The climate control turned itself on at 75degrees. I adjusted the temp and *think* I heard the actuator responding, but not sure. Either way, the interior quickly got too hot. I tried the diagnostic check again, and got a 00.

I'm going to have another look at the FSM and see if I've missed something. Thanks for all the assistance so far.

-Bill

 

[wkilleffer]

Ok, an update:

I figured out that I'd been trying to install the actuator onto the flap arm the wrong way. A little fiddling, and I got it on correctly. This *almost* solved the problem. The actuator responded to input from the ECC control panel.

But while driving earlier this evening, it seemed stuck on hot. So, I did the diagnostic thing, and got a code 105, which is the intermittent air temp valve motor circuit fault.

Trying to decide if this warrants checking the wiring in the area of the control panel. Someone did some really bad stuff in that area when they installed a fancy radio, amp, and sub. My attempt to put everything back to rights might have resulted in a less than ideal connection.

But it seems as though I'm on the right track.

Thanks, y'all.

 

[Banjo]

Here's hoping William. Sounds like you're making progress.

 

[racingenglishcars]

... actuator working reverse from that desired.

In the last case I can only describe an imaginary scenario:
It could be that when the interior gets hot, the resulting actuator motion would move for example out. If the flap is made so that when the actuator moves out then temperature gets hotter, then the control system is reversed. It would (in this imaginary case) need reversing so that when the actuator moves out, the flap would move towards the colder direction.

Looks like you got it Hurray.

 

[wkilleffer]

Well, I kinda got it....

It still wants to default to heat, and now, even with the temperature set at the lowest setting of 60degrees, it will blow boiling heat for several minutes before switching to cool.

The PO said that was why he unhooked everything, and that it would switch to hot from cold on a hot summer day.

Makes me wonder if the interior temp sensor may be bad, even though the diagnostic thing isn't showing any codes. Exterior sensor seems accurate.

 

[Banjo]

In 93 the diagnostics were really just for an aid. they weren't extremely accurate. You may have a problem that is just outside the "fail" parameters of that system.

 

[wkilleffer]

In 93 the diagnostics were really just for an aid. they weren't extremely accurate. You may have a problem that is just outside the "fail" parameters of that system.

The FSM mentions being able to enter a deeper level of checks and diagnostics by pressing the WARM button after entering the OUTSIDE TEMP/BILEVEL diagnostic mode. Doesn't give many details. Any idea of what can be done in there? Cause alot of problems?

 

[racingenglishcars]

Even OBD can be fooled by poor electrical connections, not to mention the control system itself.