Uploaded March 2024 | Updated September 2026, 2 weeks ago
Warning: not really a how-to and contains rambling. Don't watch if you have a rambling allergy or tendency to be obnoxious as a response to rambling videos. Still here?
On this installment of the Naughty Truck Newsreel from Nitwit Garage, your host and narrator looks into what's gone wrong with the driver's side blend door actuator on his 2007 Chevrolet Silverado Classic. I really can't complain -- the thing lasted over sixteen years, almost 260,000 miles and through countless cycles. And the replacement part sure was cheap!
If you have a similar truck (at least from model years 2002-2006 and the 2007 Silverado Classic) with the RPO CJ3 dual zone manual climate control system, you can likely reset all of the actuators by doing the following:
1. Set the blower speed to 3. There's no need to have the ignition on.
2. Pull the HVAC/ECAS fuse.
3. Wait TWO WHOLE MINUTES at least.
4. Put the fuse back.
5. Turn the ignition on. There's no need to start the engine and you may not want want to, in case doing so interrupts the microcontroller's "relearning" efforts. Just wait. The blend door will move through its complete range of travel twice. Be patient (notice a theme here?)...
6. Test to see if the blend door now works correctly.
You need a 5.5 millimeter stubby nut driver, which you probably can't actually get. I later asked the Keykeeper if he had such a thing that I could have stolen, and he did not.
If you have an actuator with a failing resistive track, performing this recalibration may buy you some time, though the fix is not likely to last. You may also have to do this if your truck's battery fails or after something like a jump start.
The IC inside the module is a TCA0372 operational amplifier. One of its many applications is for use as a bidirectional motor controller. See the datasheet here, complete with an example circuit that's probably very close to what is done in this module: onsemi.com/pdf/datasheet/tca0372-d.pdf .
I am well aware that both the airbag fault and service engine soon lights are both on, as I have these crazy things called "eyes" that let me see stuff. (They are also kinda handy for driving, if you can believe it.) As it's important that the airbag work so it'll keep you from getting hurt in a crash by breaking your face when it goes off, I would gladly fix it. However, it seems that new replacement sensors are no longer available here in 2024. I'm not going to pay good money for a used part that might soon fail in exactly the same way. I don't know if this situation will pass, so if you're watching in the future and airbag sensors for this truck are available at the bottom of cereal boxes, just know that they weren't when I wrote this and I'm probably far too lazy to go back and edit it should things change.
I don't care that the "check engine" light is on, and I ***really*** don't care that you care about its being on. If you really care that much, the code is for a minor evaporative emission control leak. I don't care to spend the rest of my waking life trying to find said leak, and after having asked several mechanics about doing the same, they didn't seem really enthused by the idea either. Now you know. Get off my lawn.
Not mentioned but explored in this video was the possibility of abusing my refrigeration service wrench to drive the 5.5 millimeter bit. It didn't work.
0:00 Intro
0:15 No affiliation with other "nitwit garages", if there are any.
0:40 What's gone wrong this time?
2:03 Temporary Workaround
2:51 A primer on appropriate tool use.
3:09 Tool Dichotomy: Hammers and Chisels
4:03 Borescope Exploration!
6:20 It's a boy!
6:50 Manual blend door operation.
6:58 Much ado about plugging in the old actuator.
7:23 Fault demonstration.
9:29 Super Krappy Part
12:04 Boldly going where no Scanning Electron "Candyham" has gone before!
12:37 What, why and how it works.
15:03 New actuator in operation
15:33 Recalibration Process
17:33 Thank you for watching!
Warning: not really a how-to and contains rambling. Don't watch if you have a rambling allergy or tendency to be obnoxious as a response to rambling videos. Still here?
On this installment of the Naughty Truck Newsreel from Nitwit Garage, your host and narrator looks into what's gone wrong with the driver's side blend door actuator on his 2007 Chevrolet Silverado Classic. I really can't complain -- the thing lasted over sixteen years, almost 260,000 miles and through countless cycles. And the replacement part sure was cheap!
If you have a similar truck (at least from model years 2002-2006 and the 2007 Silverado Classic) with the RPO CJ3 dual zone manual climate control system, you can likely reset all of the actuators by doing the following:
1. Set the blower speed to 3. There's no need to have the ignition on.
2. Pull the HVAC/ECAS fuse.
3. Wait TWO WHOLE MINUTES at least.
4. Put the fuse back.
5. Turn the ignition on. There's no need to start the engine and you may not want want to, in case doing so interrupts the microcontroller's "relearning" efforts. Just wait. The blend door will move through its complete range of travel twice. Be patient (notice a theme here?)...
6. Test to see if the blend door now works correctly.
You need a 5.5 millimeter stubby nut driver, which you probably can't actually get. I later asked the Keykeeper if he had such a thing that I could have stolen, and he did not.
If you have an actuator with a failing resistive track, performing this recalibration may buy you some time, though the fix is not likely to last. You may also have to do this if your truck's battery fails or after something like a jump start.
The IC inside the module is a TCA0372 operational amplifier. One of its many applications is for use as a bidirectional motor controller. See the datasheet here, complete with an example circuit that's probably very close to what is done in this module: onsemi.com/pdf/datasheet/tca0372-d.pdf .
I am well aware that both the airbag fault and service engine soon lights are both on, as I have these crazy things called "eyes" that let me see stuff. (They are also kinda handy for driving, if you can believe it.) As it's important that the airbag work so it'll keep you from getting hurt in a crash by breaking your face when it goes off, I would gladly fix it. However, it seems that new replacement sensors are no longer available here in 2024. I'm not going to pay good money for a used part that might soon fail in exactly the same way. I don't know if this situation will pass, so if you're watching in the future and airbag sensors for this truck are available at the bottom of cereal boxes, just know that they weren't when I wrote this and I'm probably far too lazy to go back and edit it should things change.
I don't care that the "check engine" light is on, and I ***really*** don't care that you care about its being on. If you really care that much, the code is for a minor evaporative emission control leak. I don't care to spend the rest of my waking life trying to find said leak, and after having asked several mechanics about doing the same, they didn't seem really enthused by the idea either. Now you know. Get off my lawn.
Not mentioned but explored in this video was the possibility of abusing my refrigeration service wrench to drive the 5.5 millimeter bit. It didn't work.
0:00 Intro
0:15 No affiliation with other "nitwit garages", if there are any.
0:40 What's gone wrong this time?
2:03 Temporary Workaround
2:51 A primer on appropriate tool use.
3:09 Tool Dichotomy: Hammers and Chisels
4:03 Borescope Exploration!
6:20 It's a boy!
6:50 Manual blend door operation.
6:58 Much ado about plugging in the old actuator.
7:23 Fault demonstration.
9:29 Super Krappy Part
12:04 Boldly going where no Scanning Electron "Candyham" has gone before!
12:37 What, why and how it works.
15:03 New actuator in operation
15:33 Recalibration Process
17:33 Thank you for watching!
