Thread: [?] blend door actuator or HVAC control unit ???

2003 pontiac grand prix GT with dual climate control unit with DUAL SLIDERS.

recently started having the passenger side blow HOT when slider is set to COLD. sometimes i could wiggle the slider up/down one notch and get it to start blowing cold, but it's completely random.
i removed the passenger side actuator and inspected the gears. everything looks good (link to photos below): Photo Album - Imgur

i then disconnected the battery for 15min and reintalled the actuator (so the computer could reset the actuator). i then turned the car on with everything installed and moved the slider between hot and cold to verify the actuator was functioning. the actuator was moving but upon releasing the slider the actuator would continue to move or "hunt" on it's own ... moving back and forth between hot/cold settings and would not settle into the full cold location as set by the slider (and thus continue to blow out hot air instead of cold AC from passenger vents).

would this behavior stem from a problem with the HVAC control unit itself? or maybe the solonoid within the actuator (since the gears are not broken and the unit)? is it possible there could be a loose connection somewhere on the back of the HVAC control unit, or would this behavior indicate something internally to the HVAC control unit? thank you -

that's the cheaper option (vs replacing the hvac control unit) so in essence that is what i wanted to hear

Originally Posted by Scottydoggs

change the actuator its dead, thats what they do. its the motor inside it that broke, nothing else.

the silver solenoid device, you mean?
just ordered one from ed morad for $30 - i hope this solves the issue. thanks again for the speedy replies.

disconnected negative terminal (was disconnected ~15min)
replaced actuator with new (used/tested) unit
reconnected everything
turned dual sliders to HEAT
turned on vehicle
turned on fan to max speed
verified hot air blowing out of vents
slid to COLD
visually watched the motor turn the door all the way to the cold (clockwise) position, and once again continue to do the same thing and "wander" around and finally settle on a warmer/HOT setting.

any ideas what to check for next? an issue from the hvac unit itself?

purchased from morad-parts and it was tested before shipped, or so im told.
inspected the innards and the gears looked in great shape - must be another bad motor?
i will ask for another unit to try out.

are you sure there is not something with the hvac control (maybe the slider connection?) that could be at fault?

a new(used) tested unit arrived and after reconnecting everything the same "wandering" is happening.

looks like i will be replacing the control module itself ...

is there anything i can check on the hvac control module itself? any connections or anything of that nature?

[update]
purchased new (used/tested) hvac climate control module
no signs of wandering door actuator. so far so good.
and then i noticed sometimes when i would first turn on the car and then first turn on the fan/blower (from off to 1), i would lose power to my driver information control (which is hacked into my gt as my vehicle did not come with the digital one (just the dummy DIC) - and the power is drawn/tapped from the stereo/hvac connection). i also noticed the light for the AC would sporatically go on/off (the AC would remain on) ... and to the point i could push against the face of the HVAC unit (near the AC button/light) and applying pressure would get the AC light to come on, and releasing would turn the AC light off. suspecting the unit, although fixing my actuator door problem, has a new internal power/electrical-short problem of itself. time to replace/refund and try again.

i put my old (original) hvac control center back in and im still seeing the electrical issue.

when i turn on the vehicle, the first time i turn on the fan/blower, i lose power to my DIC (tapped into my HVAC) and also i hear a "clicking" from the driver side dash (by the headlamp switch). and then if i turn the blower to 2-3-4/max, it will come back on and function normally. then if i turn the blower off and back on, i do not see the same power issue. it only seems to happen the first time after i turn the car on.
is there a relay or something back there i should investigate? ive been in the dash/console so much lately i think i may have a loose connection somewhere.

last week i did take apart the driver side console as i was going to pull the driver side actuator door and place onto passenger side, but by the time i got down there it looked a bit too tedious so i left it alone.

update:

so the first replacement (used/tested) unit that i procured above was sent back due to possible internal issues (ac button light) ... but that replacement unit still exhibited the passenger side door actuator issues (even after replacing actuator).

a 2nd unit was received and with the same actuator in, i have not yet experienced the issue yet over the past week. so quite possible it was the hvac unit the entire time, but wouldn't make sense why the 1st replacement also imposed the same issue. time will tell.

I have a 2001 GTP. I am reviving this thread as I am having a similar issue. Steps taken so far:

1. Last month I noticed the A/C was not blowing as cold. Using an A/C pro bottle I checked the pressure and it was a little low. I recharged it with A/C pro bottle. It worked better for a couple weeks. Then I started noticing that the drivers side was not getting cold at all while the passenger side was cold.
2. Following a forum post this one, I assumed it was the blend door acutator. I went ahead and bought one from the local parts store. After taking off the bottom part of the dash I was able to get under far enough to see the drivers side actuator. I took the plug out of it and plugged in the new part just to test it before trying to install. During testing it moved as expected when adjusting the driver's side climate control temp gauge on the dash. Though, after running the car for a awhile, it would not blow hot when set to hot and not blow cold when set to cold. It seems to only blow the ambient outside air temp. I returned the plug to the old actuator, and was able to watch as that one turned as expected too when adjusting the temp controls.

Now I am at a loss of why the drivers side does not blow hot or cold while the passenger side works with no problem. What else should I be troubleshooting? The dash temp control unit seems to indicate it works fine if it is making the actuator move, right?

my issue has been solved by the replacement of the analog dual-slider HVAC control module.