Different HVAC problem?

[BubbzWasHere]

I just picked up a 2003 Trailblazer LT and have the very well documented HVAC blend door issues. The truck has the dual zone auto climate control. When I got it, I only had defrost and feet, nothing out of the dash vents. I tried the recalibration 4 or 5 times with no luck. I bought a new blend door actuator off of Rock Auto and had the techs at my work replace it. Let me just say that these aren't general techs or chevy guys. It's a Jeep shop that I work at and that's pretty much all they work on. I say that to say that something could have been done wrong.

When they got in there, they found the blend door actuator unplugged. Plugging it in just led to clicking so they started the process to replace the actuator. They got it in and now I have dash vents. The problem now is, I always have dash vents. No matter what setting it is one, air blows out the dash vents unless I close them. It does switch to defrost and feet, but is always coming out of the dash too. I don't get anything though out of the side defrost vents(the ones for the windows). Anybody have an idea of what is wrong here? Did it possibly not get aligned right? If they plugged it in before installing it(don't know if that happened or not), would that mess up the actuator? I've tried the recalibrate after the new actuator was put in and it doesn't fix it.

Thanks for any and all help! Hopefully I didn't miss something in my searching. I couldn't find anything where the dash vents always blow air.

 

[TJBaker57]

First I would ask precisely which actuator was replaced. The blend door actuators mix temperatures, they do not control airflow direction from one vent to another. That job falls to the Mode actuator and the defrost actuator, both on the drivers side by the footwell. The actuators are also not the same part number although they will fit interchangeably, the internal workings are different in programming and cannot be reprogrammed.

 

[BubbzWasHere]

Sorry, it was the mode actuator, not the blend door. Got the wording mixed up there. The specific one I purchased was AC Delco 1573596, which has a listing of "Mode Door (Controls which vents the air comes out of); Front; Dual Zone Climate Control with Automatic Controls (you can set a specific numeric temperature) (CJ2), Front; Dual Zone Climate Control with Manual Controls (blue/red dials only), MORAINE,OH PLANT CODE(DAY), OKLAHOMA CITY,OK PLANT CODE(OKL)"

 

[BubbzWasHere]

And the mode actuator is the one they replaced. It was unplugged by the previous owner and when they plugged it in to make sure it didn't work, it just clicked a bunch.

 

[TJBaker57]

Sorry, it was the mode actuator, not the blend door. Got the wording mixed up there. The specific one I purchased was AC Delco 1573596, which has a listing of "Mode Door (Controls which vents the air comes out of); Front; Dual Zone Climate Control with Automatic Controls (you can set a specific numeric temperature) (CJ2), Front; Dual Zone Climate Control with Manual Controls (blue/red dials only), MORAINE,OH PLANT CODE(DAY), OKLAHOMA CITY,OK PLANT CODE(OKL)"

I have the same CJ2. When I replaced my Mode actuator I then discovered my defrost actuator also had some broken teeth in the gearing.

 

[TJBaker57]

I just picked up a 2003 Trailblazer LT and have the very well documented HVAC blend door issues. The truck has the dual zone auto climate control. When I got it, I only had defrost and feet, nothing out of the dash vents. I tried the recalibration 4 or 5 times with no luck. I bought a new blend door actuator off of Rock Auto and had the techs at my work replace it. Let me just say that these aren't general techs or chevy guys. It's a Jeep shop that I work at and that's pretty much all they work on. I say that to say that something could have been done wrong.

When they got in there, they found the blend door actuator unplugged. Plugging it in just led to clicking so they started the process to replace the actuator. They got it in and now I have dash vents. The problem now is, I always have dash vents. No matter what setting it is one, air blows out the dash vents unless I close them. It does switch to defrost and feet, but is always coming out of the dash too. I don't get anything though out of the side defrost vents(the ones for the windows). Anybody have an idea of what is wrong here? Did it possibly not get aligned right? If they plugged it in before installing it(don't know if that happened or not), would that mess up the actuator? I've tried the recalibrate after the new actuator was put in and it doesn't fix it.

Thanks for any and all help! Hopefully I didn't miss something in my searching. I couldn't find anything where the dash vents always blow air.

As long as they never opened up the case of the actuator and moved a gear. There is a specific relationship between the gearing and a potentiometer of sorts inside. They MUST remain in the same position as shipped. If someone opened the casing to rotate a gear to make it easier to align during install you could end up with the behaviour you are experiencing.

 

[BubbzWasHere]

I don't think they opened the case, but I wasn't watching them either. I'll have to check with them to make sure.

 

[Mektek]

I didn't see any mention of recalibrating the new actuator........

 

[Mooseman]

Check this thread where there is a diagram of all the actuators. It sure sounds like the defrost actuator is also defective.

a/c control issues 2005 TB (Front actuators/diagram)

You did do another HVAC relearn by pulling the HVAC-B fuse, replacing it after about 30 sec, turn the key to RUN and let it relearn the actuators?

 

[BubbzWasHere]

Yes, I’ve tried the recalibration twice sine the new actuator went in with no changes.