Then again if the number of steps it takes to close since it always closes on start up and if it'* already there then the code written (as in the program) in such a way that if it doesn't get a change from the position sensor (because it’* already close) may cause an error(I doubt it). It may be better to set it to the lowest temp, before disconnecting the battery. I believe this is something that is going to have to be confirmed by trial and error, but it’* close. Unfortunately since we have a bad actuator I think we should leave well enough alone on this one until the actuator is fixed (which probably become a coat hanger if it does it again).

Jeff

Agreed. (BTW, my coat hanger works great )

Ya want some bialin' twine wi' that?

Hmmm, OFF. What a concept! I would guess that to be correct, having an option.

After some verification by some members here who have a need to disconnect the battery, I would like to add an instruction in many of our TECHINFO articles to this effect. What do you think?

I am not really a member of your board, but I could see this as useful for someone with this problem. During my searches I came up with a lot of posts that didn't get me anywhere and usually ended without a solution.

BTW the 96' is being sold right now and will still "be around" but under new ownership. My friend bought a 06" GXP this weekend, it'* been sitting on the lot and has right at 8K on it right now.

Thanks again for your help on getting theis problem fixed.

Jeff

I’m a bit late getting in on this thread, but I do have a little to add…AND I have a theory. I too, have sat there with a flashlight watching the motion of my airmix door through that little hole in the dash brace.

Brief history:
My car is a ’93 and I was able to read out the error codes. They told me my HVAC programmer had gone the way of Teddy Roosevelt, so I replaced (and upgraded) with a 95 unit. I still had the flashing ECC display after this was done. Turns out the airmix actuator was the culprit, so the error codes were slightly more than useless. My ECC was doing some whacky stuff too.

A little more history:
Prior to this, it seemed whenever I disconnected my battery I’d get the flashy ECC display and the car would blow heat when I wanted A/C. [During the last failure, it blew cold when I wanted heat (winter in Utah) – how it knows to do opposite of what you need, I don’t know!]. I would ignore the flashy dash for a couple weeks and it would fix itself (my favorite method of troubleshooting). That is until the last failure (seemingly caused by another battery disconnect) this winter - my wife drove the car, blowing cold air, for a couple months until I used the redneck repair as a temporary solution - it was apparent it wasn't going to fix itself. I just recently replaced the airmix actuator and the ECC works like a champ again. I have drafted some procedures to do this…I’ll post a link later next week after the Gods have reviewed it.

Not so brief theory:
The point of the history is to lend credence to my theory. Here’* what I think is happening – why disconnecting the battery hoses up the airmix door and calibration is required. The failure mode for these actuators is a big plastic gear that drives the rod that connects to the airmix door. This gear is pressed onto a serrated shaft and after time will split.

I think, after it starts to split, this gear works OK until the battery is disconnected. As Jeff speculates, the actuator “forgets” where it’* at and when it goes through it’* little startup routine (going full cold, then full hot, then to set position) it pushes too long in the cold position and the gear slips on the shaft. Now when it drives to the hot position (the calibration position), it doesn’t open the door all the way. This is sensed by the ECC system and it sets the “calibration required” code. Because the gear can still grip fairly well, as the system is started up daily it eventually gets moved back to the correct position. (Note: there are no limit switches on the airmix door, I think it’* all done within the actuator motor circuitry). That’* why mine would “fix” itself after a while.

Once that gear splits and strips enough, just moving the door will cause the shaft to slip in the gear. This is the point that, no matter what you do, you can’t get the ECC to stop flashing. You can confirm this failure mode by taking a screwdriver and attempting to move the airmix door arm, with the airmix actuator rod still connected. If you can move this arm easily, your actuator is toast. Don’t turn into the Incredible Hulk and really reef on that arm, you might damage a perfectly good item. But if the arm moves with just a little force, you’ve found your huckleberry.

More information for anyone troubleshooting ECC problems!

Does the 2000 years have the same Hvac, and air mix actuator setup as these, I dont have a flashing ECC but I am blowing warm air on A/C and would like to troubleshoot.I know my 90sse is different.

SSE Motorhead, your analysis and investigation into the airmix door actuator problem is very good stuff! It is thorough and well written and is certainly helping us all to better understand just what in tarnation'* going on in there, lol.

I still am not sure that there isn't something that occurs when there is a complete power loss (i.e. battery cable disconnected), that is perhaps creating more stress on and leading to the gear fracture you've pin-pointed as a main failure mode. I have just been noticing too many of these that are occurring right after a power loss/shut-down.

It may indeed be that the gear has already failed and the additional stresses of the ECC reset are causing it to manifest. It may also be that those stresses are a major contributor to the gear failure in the first place. For example, yours had been powered down a number of times and reset itself each time before finally failing.

All the more reason (still based on speculation at this point I might add) that I personally will recommend that we shut our climate control systems to OFF prior to disconnecting the battery.

EDIT: jdq, I'm going to have to defer to someone with a 2000+ FSM who might know your answer.

[quote="lash"].

All the more reason (still based on speculation at this point I might add) that I personally will recommend that we shut our climate control systems to OFF prior to disconnecting the battery.

/quote]

I agree, Lash. I think it would be a good idea to turn off the ECC prior to disconnecting the battery. Problem will be remembering to do so! I don't know if disconnecting the battery would prevent the ECC from losing it'* memory (e.g. an encoder losing power and requiring reset) if the ECC were turned off first or not. Certainly couldn't hurt.

The 00+ years also use the same type of actuator.

For anyone interested in changing the air mix actuator or upgrading your 93 ECC to a 95 ECC, go to www.trialsnuts.com/ecc.pdf.

You'll need Acrobat reader to read the pdf file.