I tried to recalibrate it by pulling the HVAC fuses waited 1 min put them in put the key in the run position and waited 2 min.defrost works. Just feet work. Feet and defrost work. But feet and front vents don't work or just front vents. I don't here no clicking or anything to think a actuator went bad. What do I do?
replaced battery and now no air comes out of the front vents.
- Thread starter Zack2003
- Start date
RedEnvoyDenali
Member
- Dec 4, 2011
- 520
This is a common problem with this platform. Typically what happens is that the actuators need to re-initialize after the power is disconnected. They do this by exercising the actuators from one extreme to the other and by stalling out at each end, they can then determine where the limits are. What happens is that when they power to the end and stall out the shaft on the drive gear turns and then the actuator gets confused because it doesn't know where the end is, it just quits. Replacement is the only cure, not a fun job but doable. Several people have used a secondary battery to keep power to the actuators while changing the worn out battery thereby avoiding the problem. This method has it's own challenges.
You need to search this site for schematics and lots of comment on the process. Try "Actuator replacement" and good luck.
You need to search this site for schematics and lots of comment on the process. Try "Actuator replacement" and good luck.
Yep, it's the mode actuator. Rarely, owners pull the HVAC-B fuse for 30 seconds with the ignition off, then plug it back in, turn the ignition on but not start the engine, and wait 2 minutes for the recalibration process to run its course. Some of them do this 4-5 times and the actuator recovers. But it's still a bad actuator, and the next battery change may kill it for sure, permanently, and then it might not be in a weather pattern of your choosing. Better to change it when it's not -20 or +120 degrees, while you're at home with all tools and time, and not on vacation in Florida in July.
Just went to a buddy of mine house he has one of the computer scanners that the dealer have and this is the code it threw B0263
B3770
B3770
I'm having trouble finding good information. Mite be because I'm on my phone. But that is the Mode actuator correct? Which on the drivers side floorboard looking up it would be the highest one correct?
Many threads here if only you were on a real computer. Or maybe this link will help
http://www.sparkys-answers.com/2010/12/2004-chevrolet-trailblazer-identifying.html
http://www.sparkys-answers.com/2010/12/2004-chevrolet-trailblazer-identifying.html
Had the exact same thing happen. As the roadie points out, replace the actuator now before the extreme heat or cold. The particular actuator you need to replace is fairly easy to get to and takes about a half hour to replace.
IllogicTC
Member
- Dec 30, 2013
- 3,452
B0263 - Mode Actuator confirmed.
B3770 - Mode Actuator double-confirmed.
One code relates to attempting to move to a new position, the other is for position feedback vs. desired. She's definitely not moving.
Make sure to thank your buddy with some beverages or a pizza or something sometime. Having access to high-level scan tools makes diagnosing a lot of stuff on this platform so much easier!
B3770 - Mode Actuator double-confirmed.
One code relates to attempting to move to a new position, the other is for position feedback vs. desired. She's definitely not moving.
Make sure to thank your buddy with some beverages or a pizza or something sometime. Having access to high-level scan tools makes diagnosing a lot of stuff on this platform so much easier!
Ok it was the Mode valve Actuator took it off and saw that the gear was facing down way to far so I took it apart and took some gears out so I could spin it back to where it was suppose to be at. Put back together and it's working perfect for now!
IllogicTC
Member
- Dec 30, 2013
- 3,452
I'd consider it a "temporary" fix. Then again, the system tests the actuators by running it fully to one end, then fully to the other, I'm not sure how rough it is in doing so but it sounds rough. I'd consider pricing out a replacement one to have on-hand (or even just replace it), unless it's working well enough for you. I know they're pretty expensive though, so it's good to hear you have an interim solution at least.
Normally I would agree 100% but all the actuators I saw that were bad had a stripped gear inside. When I opened it up they looked brand new not stripped. I'm wandering if the guy I bought it from didn't do the recalibrating thing when he changed the batterie and it threw it off and when I changed the batterie it just threw it off. I could be totally wrong and it break tomorrow I just thought it was weird that the gears looked perfect
RedEnvoyDenali
Member
- Dec 4, 2011
- 520
When i changed mine everything looked fine however the shaft that attaches to the gear would spin in relation to the gear and then the calibration would be off or more correctly it would not calibrate.
However if you like changing the actuator then have at it. However the next time it might be -30 C or +30 C neither will be pleasant. I am in awe of JFKMK (hope I spelled that right) because it took me well over 1/2 hour. Time is a little more precious than $ so I replaced mine (the first time it was disconnected to put in a Remote Start). In the interim i have replaced 2 batteries and it re-initialized correctly both times Yippee no surgery under the dash.
However if you like changing the actuator then have at it. However the next time it might be -30 C or +30 C neither will be pleasant. I am in awe of JFKMK (hope I spelled that right) because it took me well over 1/2 hour. Time is a little more precious than $ so I replaced mine (the first time it was disconnected to put in a Remote Start). In the interim i have replaced 2 batteries and it re-initialized correctly both times Yippee no surgery under the dash.
Like I said a few post up I'm buying a new one but at least I have air out of my vents for now until it arrivels. And I also leaned a lot about it and how to do it. I like learning these things so that's worth my time. But you know it will only go out if it's freezing or burning up. And since the weather is perfect right now it won't go out haha
Old one is still working but I went ahead and got a new one. Don't want to take any chances. Wish me luck! Hope it calibrates right
To avoid this issue you can run a 12 volt power supply through the power port when you change the battery. It fools the actuators so they never cycle like they would if they were disconnected. My first battery change toasted mine back when it was still under warranty. Ever since that I've use a power supply when removing the battery and have not had anymore trouble.