I have a 2003 trailblazer the heat works great out of the vents and defrost but not the floor in fact the wife says she feels cold air on her feet I have I guess the basic system not electronic thanks in advance
no heat out of floor vents on a 2003 trailblazer
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So if you have the heat on hot, and the blower on high and the airflow out of the dash vents is OK, you get no hot air out of the footwell vents?
It's the airflow mode actuator. Run a search for that term or for "mode actuator" and start getting ready to take part of the dash covers off.
It's the airflow mode actuator. Run a search for that term or for "mode actuator" and start getting ready to take part of the dash covers off.
I have the exact same issue. Replaced the actuator 6 months ago for a ticking noise. Do I need to take it off with the harness connected, set it on floor and somehow manually turn it the floor door open and bolt it back on? Will that work or do I have to replace it again?
Mooseman
Moderator
Do not run it not connected to the door as this will run it beyond its normal working range and destroy it. Maybe it just needs to be recalibrated. Go to the rear fuse box and pull the HVAC-B fuse for about 10 seconds and put it back in. Then turn the key to RUN but don't start and don't touch anything on the HVAC until it has finished recalibrating the actuators.
If you have to replace it, If it doesn't go on the door shaft, rotate the actuator onto the shaft until it engages it and then turn it back to the position to allow you to put the screws back in. Run the recalibration again.
If you have to replace it, If it doesn't go on the door shaft, rotate the actuator onto the shaft until it engages it and then turn it back to the position to allow you to put the screws back in. Run the recalibration again.
Mooseman
Moderator
Mooseman
Moderator
I can't tell from the pic. Just put your hand on it and feel it clicking to be sure. The schematic above should confirm it but for driver temp, should be the lowest one.
There is another one right above the gas pedal behind the trim panel below the steering wheel. Idk which one to replace. Gonna take out the one I put In check out to see if the blend door moves freely if I can and put it back in. Does it go in a certain way or just till it engages no matter what position Its in? And which one has the white lever on it?
Mooseman
Moderator
The other one is either the mode door which selects floor/vent or the defrost door.
It's keyed. It only goes in one way. (Well, theoretically two ways but the whole actuator would have to be be upside down).
It's keyed. It only goes in one way. (Well, theoretically two ways but the whole actuator would have to be be upside down).
The two actuators in your picture are the mode actuator on the right and the defrost actuator on the left. Neither one does anything with a "blend" door. Blend doors and actuators mix cold and hot air to get the temperature setting where it is desired. The mode door actuator along with the defrost door actuator direct the air to different outlets but do not blend anything. If you were looking for the drivers side blend door actuator that one is on the drivers side ut further towards the center console and more difficult to get at.
I'm not sure about the 2003 models but my 2002 has no actuator with the white plastic external gear that is commonly seen on others.
I'm not sure about the 2003 models but my 2002 has no actuator with the white plastic external gear that is commonly seen on others.
I meant the mode actuator. The one with the white lever on the back. I removed it today and moved the black lever attached to the airbox and mode door moves freely but have to hold it open for floor airflow because it feels like it's spring loaded. Just closed when I let go. Does not appear to move when Installed and don't know if the white lever is engaged with the mode door gear. I'll just replace it again but is there any special way to put it in with the door closed? Or just put it in and hope the part actually comes with the lever in the right position. Is the door supposed to stay in the closed position?
I looked online but found no good guidance for this.
I can't speak from experience because mine is a 2002 and that year did not use that white plastic gear piece at all.
Maybe someone here has an answer It would sure seem to me just by looking at it that it must be installed with a certain alignment of the gears or it won't work.
I know thought about that but the door is spring loaded. I took it out again today, took it apart, smacked the little motor, moved the gears to align the lever to the one on the housing. Got a click noise once after recalibration of the system but there is now hot air blowing out the foot vents but barely the center vents. Will end up replacing both but feet and defrost is fine with me for now. How can you hold the door halfway open when putting the actuator in?
I just got a $1000. estimate from the Chevrolet dealer to replace the "defrost actuator" on my 05 trailblazer. Said it's a 5 hour job. Well, 1st they said 7 hour job. I called BS, I can't believe it takes that long to take the dash off, change the part and put the dash back on, I watched several videos of people doing it and I'd accept a 2 or 3 hour job for someone who doesn't have experience. Is it called the defrost actuator because no website can show me that part when I put that? I have heat/AC and defrost out of the dash vents but nothing on the floor. They diagnosed it by "removing the radio and clutch trim to access HVAC controller, pinned wiring to see what actuator was not allowing heat to switch to floor and they could see the defrost actuator is bad and not moving past vents." (exact words on estimate) but then say they have to take the entire dash apart to fix it? Sounds fishy to me. Why couldn't they just fix it through the point they accessed today if that's how they decided it was the problem? AND I have to schedule another appointment to fix it, they couldn't do it today, they had my trailblazer from 8 am to 5pm and only replaced an outter tie rod. Please help. I think my dad and I could actually do this ourselves if we can just find the right part/video.
Drop in on THIS 'On Topic' and Contemporary Thread for a Bird's Eye View of all of the Blend Door Actuators and a description (with OP images) from one of us who just performed this R&R work:
gmtnation.com
2003 Trailblazer Vent \ Recirculate Actuator
Hello all. Thank you in advance for anytime you can spend assisting me. My wife has a 2003 Trailblazer with manual HVAC system. I have to replace the Recirculate \ Vent actuator because it is not shutting off at the limits and now is making a whining noise. I was able to find out from...
gmtnation.com
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Based on what you posted, dealership or not, I would say they have no idea what they are talking about. Personally I think they days when the dealerships arguably were better shops are long gone.
Right off the bat, all the HVAC actuators can be tested with a scantool, NOTHING has to be taken apart, just plug in the scantool and all the actuator positions can be read out.
So removing the radio etc. To read pins is entirely bogus.
If your main problem is getting the the air to blow out of the defrost, panel (dashboard), or footwell vents those two actuators (Mode and Defrost) can be replaced in no more than an hours time. Only the lower drivers side cover and a small plastic duct needs to come off. I would say one hour at the most for anyone who has done this before.
Now there is one actuator that will take that 5 to 7 hours to replace and that is the "Recirculation" actuator. The function of this actuator is to let outside air into the system or just use air from inside the cabin. Has no effect whatsoever on where the air blows from.
Right off the bat, all the HVAC actuators can be tested with a scantool, NOTHING has to be taken apart, just plug in the scantool and all the actuator positions can be read out.
So removing the radio etc. To read pins is entirely bogus.
If your main problem is getting the the air to blow out of the defrost, panel (dashboard), or footwell vents those two actuators (Mode and Defrost) can be replaced in no more than an hours time. Only the lower drivers side cover and a small plastic duct needs to come off. I would say one hour at the most for anyone who has done this before.
Now there is one actuator that will take that 5 to 7 hours to replace and that is the "Recirculation" actuator. The function of this actuator is to let outside air into the system or just use air from inside the cabin. Has no effect whatsoever on where the air blows from.
Called a "Heater Air Door Actuator" on Rock Auto if you still can't find. I had good luck using the original Delco parts that I bought from Rock Auto, cheaper than dealer at the time. It was one of my 1st repairs, still working well 4 years later.
Mooseman
Moderator
I also call BS on all they said. I think they looked at the work description for the recirc actuator, like @TJBaker57 described. I think the passenger side blend door on Envoys require some cutting of the metal brace, which GM may say requires removal of the dash since they don't use shortcuts.
My truck is an 06 Envoy. I don't recall which actuator required the metal trim but I did do it that way on my dash. It was right in front of the center console. It was far easier and faster to cut the brace than to remove the dash.
Happy New Year! I, sadly, did run it without the door as it was so far out of the range - it was in the center position and the door was all the way to the cold side due to the dashpot forcing it down. (Default mode?) I figured I would just let it move to the cold side and slide it on. However, it just banged against the hard stop on the module. I can move it back with a battery to the center position. The position sensor seems to be working just fine.
Did I really damage it or can I try again and do what you wrote above?
Mooseman
Moderator
It may have been damaged or was outside the range of movement of the door and was possibly damaged if it was at that extreme end of the range when you installed it. You can try doing the relearn again while it's installed and see if it works.
I appreciate the reply. It is so hard to work on given the location and that darn metal bracket in the way, but I'll give it another go tomorrow. Are there sensors attached to the doors as well? I can see the actuators working more like servos with internal potentiometers for feedback control.
I don't see a posting describing exactly what your issue was/is and which actuator you are dealing with.
Which actuator are you working with?
Is it a new part or existing part?
Have you ever opened up the actuator where you can see the plastic gears and so on? If so it is imperitive you do not remove and relocate any of the gears inside without the specific knowledge of how they MUST be properly indexed/aligned with each other (assuming you are working with an original designed part). Using the original design this can be done BUT you MUST know how to do it properly or it will never work right.
It's the heat control actuator - driver's side. Always cold. I have a new one and I am fighting the installation procedure. I did take the old one apart for fun. I work with controls systems so this was interesting.
So assuming you have the original designed actuator, and having seen the insides with a background in controls you likely recognized the geared potentiometer of sorts that engages the final drive gear. That needs to be at it's center when the drive gear is also at the center of its' movement. There are a few images depicting this on the web including this site here. Some users have measured resistances to determine the center but it usually is good enough to just visually follow the images posted.
I have seen an aftermarket actuator where they incorporated the potentiometer (or equivalent) into the final drive gear, eliminating the possibility of a mis-alignment.
Since a great number of these actuators are physically the same one must be certain they are using the correct part number to start with for their year and style of control system, manual or automatic. For example the passenger side temperature mixing actuator will readily fit at the drivers side temperature mixing actuators' location, but it will never work correctly. The circuitry is different. One sides positional counts increase for hotter air and the other sides counts decrease for hotter air.
Thanks. I will double check the part number. I did get a few different ones at the same time (parts cannon philosophy 😺), but it is possible I grabbed the wrong one.
Yeah, it's the mode selection actuator, floor vent never opens. I'll try to put a third one in but, since weather is cold here now, will it work if I unplug and remove the actuator and manually zip tie or rig it up to keep the floor door open? I only need defrost and floor. Will that work until I can get another one? It's the actuator with the white gear on the side. Can I force it all the way open or maybe just halfway do I get airflow to the defrost?