Syncing the HVAC steppers
Syncing the HVAC steppers
As part of an add-a-chronograph project (which was successful) I had the two center dash vents removed, and the center speaker/vent panel from the top of the dash removed.
I observed that there are actually switches on the manual **** controls for the center dash vents (the ones on either side of the PCM) besides wiring for the illuminated "dash" on the ****.
Wondering what those were - I looked at the top center vents - one above each dash center vent. Turns out - the **** on the left side - when the vent on the dash was closed -- the vent on the top of the dash would open. The right side didn't behave this way.
The vent on the dash top - left exhibited resistance to moving by hand - so it was obviously connected to a stepper motor. My service manual confirmed this - showing a stepper motor for each of these vents. The right side moved easily - it had come disconnected from the stepper.
I finished my clock project (works!) - and didn't return to this for a day or so. I finally found that the lever arm from the stepper controlling the opening/closing of the right center top vent had come out of the vent assembly.
It took a LOT of fiddly work to get the arm back in position. I finally made a hook shaped tool that let me do it. The vent now sort of responded to the switch on the center-dash-vent **** - but seemed to try to travel too far and jammed up (which had probably caused it to come apart in the first case.)
I vaguely remembered that my iCarScan diagnostics tool had some procedures for the stepper motors - basically to teach the car what motors were installed, and to teach the motors and controllers what their start/stop positions were.
Turns out I was correct - the software has a program to trigger a stepper motor learning routine. I executed the routine and could see (and/or watch/or hear) all of the steppers going through their full range of travel. Did it twice just for good luck.
It worked. The upper-dash-right-center-vent now opened and closed correctly. The surprise was - how much better the entire HVAC system seemed to behave. The air quantity from the two center (PCM level) vents was now uniform for the first time. It seemed all the functions worked better.
I imagine the Durametrics may also have this capability, but didn't bother hooking it up to see. It's much simpler to plug in the iCarScan and connect to it Bluetooth through my phone.
YMMV - but if you have uneven air distribution, it's worth trying this first (or have the dealer do it for you..)
I observed that there are actually switches on the manual **** controls for the center dash vents (the ones on either side of the PCM) besides wiring for the illuminated "dash" on the ****.
Wondering what those were - I looked at the top center vents - one above each dash center vent. Turns out - the **** on the left side - when the vent on the dash was closed -- the vent on the top of the dash would open. The right side didn't behave this way.
The vent on the dash top - left exhibited resistance to moving by hand - so it was obviously connected to a stepper motor. My service manual confirmed this - showing a stepper motor for each of these vents. The right side moved easily - it had come disconnected from the stepper.
I finished my clock project (works!) - and didn't return to this for a day or so. I finally found that the lever arm from the stepper controlling the opening/closing of the right center top vent had come out of the vent assembly.
It took a LOT of fiddly work to get the arm back in position. I finally made a hook shaped tool that let me do it. The vent now sort of responded to the switch on the center-dash-vent **** - but seemed to try to travel too far and jammed up (which had probably caused it to come apart in the first case.)
I vaguely remembered that my iCarScan diagnostics tool had some procedures for the stepper motors - basically to teach the car what motors were installed, and to teach the motors and controllers what their start/stop positions were.
Turns out I was correct - the software has a program to trigger a stepper motor learning routine. I executed the routine and could see (and/or watch/or hear) all of the steppers going through their full range of travel. Did it twice just for good luck.
It worked. The upper-dash-right-center-vent now opened and closed correctly. The surprise was - how much better the entire HVAC system seemed to behave. The air quantity from the two center (PCM level) vents was now uniform for the first time. It seemed all the functions worked better.
I imagine the Durametrics may also have this capability, but didn't bother hooking it up to see. It's much simpler to plug in the iCarScan and connect to it Bluetooth through my phone.
YMMV - but if you have uneven air distribution, it's worth trying this first (or have the dealer do it for you..)
Last edited by deilenberger; Dec 12, 2016 at 01:24 PM.
