Thread: Blend Door Actuator Replacement

Originally Posted by coolio

I have a 2006 Grand Prix with the 3800 in it with a standard HVAC (single zone and manual temperature change). The heater will only blow lukewarm air (at best). I have checked the coolant level, changed the thermostat, and verified that the blend door is free and the actuator is working properly. I have also checked the heater core supply and return hoses. The supply line has good pressure and runs hot, however the return only trickles coolant when I disconnect it. It's been too cold for me to flush the system. Does this sound like a clogged heater core? In my research it doesn't look like there is a heater control valve, which sounded like a good solution to me. Any thoughts? Thanks in advance.

you need to flush the core.

Wow, this operation seems MAJOR. Wonder what the auto repair shops charge where they use that guy who has the small hands.

I have a 1992 Grand Prix that's always been a great car until we brought it out of storage. Suddenly, the heater works (warm air good) and fans work (range of speeds 1 thru 4 also good) and the Off switch works in terms of shutting off the fans but the problem is that it doesn't matter if I push the button for 'heat', 'vent', or 'defrost', etc; the air is pretty well split between the floor and the windshield and never goes full floor, full vent, full defrost, etc. And worst part now, the AC doesn't work either.

Here's a picture of the control: http://home.nctv.com/ajns/92GrandPrixHeaterControl.jpg

I have air blowing through the heater (at bottom floor board area) and defrost ducts at the same time but haven't been able to get the heat through the dash 'vent' locations and have been advised that the "blend door actuator" is probably the reason. Is there a way to 'cheat' the system and run a work around to get the AC compressor to work without going through a major job of tearing into the dash (and then risk it being something else anyway... ) ?

TIA

the blend door actuator controls heat or a/c. its what makes the air warm to hot or cold.

the part that moves the air flow direction is the round vac pump part, its round in the lower right of the pic in the first post.

theres a vac line off the engine to the fire wall on the pass side. make sure its hooked up, (it makes the air flow direction work) not sure where it goes on your engine.

the blend doors control only the mix of hot and or cold air. sounds like you have a bad fan or resistor.

so you dont have to calibrate the blend door actuator? i remember back in school, you had to calibrate them, or they would wig out and go back and forth or try and keep turning when vent was already closed or full open and break itself.

i see some dial lines on the case of the actuator and slots to use a flat head to turn it.

i plugged them in, then worked the heat to cold. ( watched it working) turn it to full cold, or hot, then turn the knob the same way, slap it back on.

taking the battery off for 30 minutes can reset them sometimes if they are doing the freak out deal.

thanks. FYI swapping digital hvac contol modules fixed my problem with air blowing out of all vents, now replacing blend actuators and charging AC

will report back with further findings.

p.s. im not getting air out of the furthest passenger vent. i swapped vac pump, have not tested yet. still have everything apart. any other ideas just in case this does not fix?

FYI my original HVAC module had a green display and has a A/C button, this module has red dispplay and "ECON" in place of the "A/C" button. it came out of a 98 model, i have a 97, dontn know if that would have anything to do with no air out of further passenger vent.

did air used to come out of it? maybe its clogged with a mouse nest, yuck......

the air is carried by plastic ducks and flex tubes, maybe it fell off the back of the vent? or ripped.

while its all a part now would be a good time to look and make sure.

my passenger side actuator had a cracked gear, replaced it but im having trouble getting them to close the doors completely. plus im back to air blowing through all vents, its very frustrating, and module does not switch from recirc to outside and vice versa. all vac lines are right, no leaks. im about to sell this damn car.

if anyone would, take a picture of the blend door actuator open so i can see the inside gears, so i can manually calibrate mine, ive messed mine up and need to see where the position sensor gear is relative to the drive gear.

also can someone take a pipc of the interior fuse block with the HVAC Control fuse (20a) should there be two pins the fuse plugs into. mine only has one terminal the fuse plugs into. could this be the reason im not getting mode actuator movement? but my HVAC Module has display and moves the temp actuators.

you could test the plugs to the actuators for power.

inside is just a bunch of gears, a big one and a smaller one. looks kinda like a gear reduction set up.

you can turn the actuator with a fat screw driver, put it in the hole and turn it. ( slowly) no need to take it apart to calibrate anything. it either works or dont. like i said, i plugged my used ones in and worked the controls hot to cold to make sure it worked. they only move a small amount. and slowly.

after you take your off, make sure the little knob it turns turns freely too.

and if you pull that fuse if your climate control goes black, the fuse is working right.