Originally Posted by joe.heathfield
For all of you that asked, it is a 1996 SE. It appears that the reply from Charliemax explains what the system is doing and I am hoping it is in a relearn mode like he explains. I am going to attempt to do what he suggests this morning and will keep you posted. It'* amazing that there is nothing about turning off the AC system and having to reprogram ECC after a battery disconnect event in any books or even the owners manual! Thanks for your help!
These ECC'* and the associated air flow systems behave in a virtually organic way. They are more like plants, than engineered devices and mechanicals. I don't know if sentiments have changed, but the majority of us who have them are just happy if they can get heat when it'* cold, and a/c when it'* hot. Precision "Climate Control" is very rare.
See how the "learn" goes. If you need a lot of starts and aren't getting decent results.. the actuator arm, which the guys mentioned above, is a likely culprit. It is sticking for some reason.
The one in my "98 SSEi, definitely has the stinkin' compromised gear. It is only replaceable and not repairable. Which means i either tear most of the dash apart for a clean replace, or I do a Helen Keller blind replace, by feel, from under the dash.
I did what used to be called a "redneck repair". If you just pull the glove box, there is hole in the back where you can see the arm operating. I could see it wasn't open/closed properly, so i took a longhandled, diagonal headed, crescent wrench... with the ECC operating at what should have been a decent heat level.. I shoved and jabbed the arm around 'til I got a hot flow.
Again I'll repeat, those arms get caught because of the full range use of the stinkin' plastic gear during the "learn". If you get snared by it, the object is to get the damaged part of the stinkin' plastic gear, out of a normal and satisfactory operating range. A "normal" range is less than the full 360* of the stinkin' plastic gear.
If the stinkin' plastic gear has broken completely or close to it... you may have to leave the wrench in place and adjust it by season. Then it'* called the White (Brown or Black etc, depending upon your ethnicity) Trash repair.
I jest, but the programming of the ECC is so overengineered, that if one area is screwed up, the ECC starts making assumptions which aren't true, and your HVAC system will develop weird habits.
One example is the "Mystery Fan". Should you have the bad fortune of changing to a 180* thermostat during a protracted period of extremely cold weather, ...and you have an excellent cooling system and a fast thermostat which prohibit the coolant temperature from ever going above 185* for more than a few minutes... when the fan should be blowing, the Mystery Fan will work at its own discretion. Sometimes blowing, some times not at all, sometimes suddenly starts blowing 15 minutes after it should have started.
This behavior is often attributed to the blower control module or the blower motor itself. And if not during this rare confluence of the events I mentioned, it probably is one of those.
What is happening in the scenario I outlined... the ECC is noting that it is very cold out and it is growing more tentative (actually restricted) about blowing extremely cold air past the heating coils, because the operating temperature of the coolant system doesn't spend enough time in the anticipated transfer temperature range of 195*. To over-simplify, the ECC doesn't want to blast you with what it assumes will be cold air instead of heat, plus hold the operating temperature of the car below minimal extended operating temperature requirements.
Two years ago, I froze my wife going to work for more than a week. I really wanted the 180* stat in the car, because the car was had a history of going through UIMs like some people change their underwear. I finally threw in the towel and swapped a 195* stat back in. The Mystery Fan disappeared fairly quickly.
So these things are funky. The good thing is there is usually a workaround.