1995 battery change/HVAC fault question

After battery change (heater was ON), heater works fine driver's side, blows cold air passenger side (inside air temp flashing). I understand that it will take 50 ignition cycles to reset. I learned that from a previous HotZ28 post on another issue. My question is: Why does it take 50 ignition cycles? What takes place in the system that 50 ignition cycles will remove code/fault? I am an old guy and not car computer savvy.... so go easy. Thanks.

After battery change (heater was ON), heater works fine driver's side, blows cold air passenger side (inside air temp flashing). I understand that it will take 50 ignition cycles to reset. I learned that from a previous HotZ28 post on another issue. My question is: Why does it take 50 ignition cycles? What takes place in the system that 50 ignition cycles will remove code/fault? I am an old guy and not car computer savvy.... so go easy. Thanks.

The flashing air temp indicator should go off after 90 seconds. Mine flashes anytime below 30 deg or so when I start.

Usually the problem on the dual temp system is the small actuator motor for the passenger side blend door on top of the heater box has cracked a plastic gear inside. That is slipping on the axle and the electronics can't index correctly. You can take off the plastic panel above the passenger's legs and watch the upper link from the actuator for movement while moving the temp settings for passenger (and driver) with the ignition ON. Or you may be able to move the link with no resistance from the actuator motor if you push on it with something.

http://i86.photobucket.com/albums/k110/imidazol97/HeaterCore1-2.jpg

Passenger actuator is in the red circle area. To the left you see the white plastic arm that moves the passenger side blend door inside the heater box.

Yes sir, you are correct. I have already tested the actuator by manually scrolling the temp from 60 to 90 degrees (and back again) and observed the actuator working smoothly. I think I am still within the 50 ignition start cycle and am waiting out my 50 ignition sequences. I am curious as to why it takes the system/computer? the 50 ignition cycles, etc. What actually causes the thing to straighten itself out? Thank you for your reply.

What the system is doing during these 50 ignition cycles, is trying to recalibrate. It can not do it the first few times, the fault will still be found. Sometimes it takes less than 50 & sometimes more, depending on how long it takes to find the home position. On some vehicles, I have been able to get quicker results by moving the temp setting from 90 to 60 while driving, this keeps the system active and speeds recalibration. In addition, switch from AUTO to Defrost (with a long pause) several times while the engine is running. This gives the system a full workout which also seems to speed up recovery.

Thank you for that. I find that my system/module/computer? is trying. I am able to get heat both sides by scrolling back to 60 and then up to 90 now. It tries to do the right thing when I first start up but then goes wacky. I will do as you recommend and thanks again for your experience.