I found this video showing the calibration procedure without using the scan tool.
HVAC Automatic Blend Motor Actuator Recalibration Procedure for GM Trucks & SUVS FOR FREE - YouTube
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There are several videos on calibrating the actuators on YouTube. Here is a picture of the inside of the actuator. The gear the arrow is pointing too is mounted on a microchip. I believe this is what you are calibrating when you do the procedure.
I would think the microchip would tell the motor how much to turn in each direction.
Not exactly, it just tells the motor when the door matches the position of the slider on the control panel. It does tell the motor which way to go to get to that position though. But it doesnāt tell it how much, just which way and when itās there. Kinda like marching, you go the direction youāre told to go until you are told to stop.
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Here is the calibration procedure, or itās the one I used on my 2005 Sierra. I donāt think youāre supposed to power up the actuator until after itās installed, or it will move past its limits. May be wrong on that, but seems like I read it somewhere at some point.
Did you say the blend door itself is physically broken also? Thereās a company called āheater treaterā that makes something that might work if you canāt or donāt want to disassemble the entire dash. No experience with them. Buddy with a Ford said it worked well at one point to fix his blend door.
Edit- looks like they donāt make a GM specific blend door repair kit. Also looks pretty pricey for the hack that it isā¦
Iāve seen that warning, but installing it just connects the blend door to the actuator. That will not stop it from going past its limits, it will just break the blend door. There are no sensors on the blend door itself, itās just a flap.
Dammit, Keith, you canāt argue with a warning sticker!
Iām kidding! Iāve never delved into how those actuators work, exactly.
Yes, if it was a stepper motor. That doesnāt look like a stepper motor to me though. Looks like an ordinary DC motor.
Yes, only two wires. On some of the actuators, the three wire control is under the large output gear. The gear has contacts on its underside.
Update, I took the two pieces of the blend door shaft that broke off and used two tiny drops of super glue to tack them together. The I got a piece of 5/16" dowel rod and filed/sanded two flats on it so that it fit in the center. I cut it to length so that it went most of the way up into the blend door and then epoxied the whole thing together.
I used JB Weld, the slow setting hard stuff. Well a tiny bit squeezed out and bonded with the housing so the blend door was stuck. Fortunately it wasnāt much as I was able to free door so it works now. All I have left is to calibrate the new motor and install it.
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Update: This is not going well.
I did the calibration again but did not install the actuator, just plugged in the connector. When I put the fuse back in and started to truck, the actuator turned toward the cold side and then reversed and went out of range. After the two minutes, I shut down the truck and 15 seconds later restarted it. The actuator moved back to the cold side and then reversed again and went out of range to the hot side.
Iām thinking that maybe with out the actuator attached to the blend door to limit its movement, when it gets out of range, it doesnāt know what to do. So I pull the fuse again and while I have the fuse out, I go to mate it to the blend door. The Genuine GM part doesnāt fit. I fit tested the old aftermarket actuator and it fits OK so I thought Iād try to recalibrate with the old one in place, but it started raining so that is where I am right now.
I was always under the impression thatās what the warning was for on the actuator that states not to power it up before itās installed. When you do the calibration, itās normal for the blend door to cycle between full cold and full hot (within range).
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The reasoning behind my decision is that the first replacement actuator when out of range and broke the actuator door. I figured that the door is only a mechanical link, there are no sensors in the door itself so it should calibrate door or no door.
IMHO, this is bad engineering on GMās part. The limits on the actuator should not be so far out of range from the blend door that it can break it. The actuator has positive stops on it, they should be a lot closer to the door limit.
Youād think so, yeah. I donāt know if the actuatorā¦is just supposed to be weak enough not to (theoretically) break the door, or what the idea is.
I think this is the actuator you need. AC delco 1572791. Be sure to specify Silverado Classic (which you probably know).
Sorry, did you mean 1572971? And why so expensive?
Iāve been spending a little time on Rock looking at part numbers the last couple of days trying to decipher the heater hoses I need. There are about 8 of them. Tee to pipe 1 etc. And the GM parts diagrams donāt list all of the part numbers. Iāll just order all of them.
Did I tell you about our Ma Bell telephone rep that was always getting our phone orders screwed up. We found out she was dyslexic. No problem with that but can raise havoc with phone numbers.
Maybe so, sorry. I clicked on the part and linked to it, but when I opened the link in the post, the part wasnāt selected. I went back and edited the post to put the part number in and may have transposed numbers. Donāt know why itās so expensive compared to the others, but thatās not too uncommon with oem vs aftermarket. I usually try to go oem with electronic stuff due to past disappointment with aftermarket.
Iāve notice this problem myself, not with the telephone company in particular, but in general.
Hereāe how a typical telephone conversation goes
Staff: What is your name and account number?
Me: George [letās say āSmithā], account number 1387976
Staff: Thereās no Mr. George associate with that account number!
Me. My name isnāt Mr. George, it is George Smith.
Staff: OK Mr. Smith, but thereās no account with that number associated with a Mr Smith
Me: What account number are you referencing?
Staff: The one you told me
Me: Which was?
Staff: 138967
Me: Thatās not what I said. Its 1387976.
Staff: That account is registered to Mr George Smith, not Mr Smith George.
ā¦ lol ā¦
Mr. Smith rolls his eyes.
The BP card is changing banks. The only thing I use it for is for automatic billing for the BP Motor Club. So I get an urgent letter to call them to provide a new credit card to use. Took me four times. First time no one home call back during business hours. 2nd, hello hello anyone there? 3rd attempt, please hold-music, then quiet. 4th attempt, I donāt speak Spanish but we made it through-I think. Weāll see.
And of course like every business, this call will be recorded to insure customer satisfaction. Donāt insult me. No way you could listen to that and not put someone without a heavy Spanish accent on the phone.
In comparison, a few weeks ago I had to do a self install of cable box. They said it would be easy. I had to call because I only got one and have two TVs on cable. On comes a guy on the help line, clear as a bell. What a relief.
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I have the custom floor console D07 so I ordered 1573620. This is the one that doesnāt fit because the shaft receiver is too small. I do not see why this makes any difference because they all look the same. Retail from a dealer on the AC Delco part is over $200.
Reminds me of when I had a 79 Dodge Colt. I needed a new vacuum advance. It was dealer only but a typical vacuum advance at a parts store would have been around $3. This one cost over $30 at the dealer. I asked the parts guy how they could afford to sell a car for $4995 when the parts for it cost over $50,000. I was told to leave and not come back. No sense of humor.
I think the one you ordered is listed as a āmodeā door actuator (defrost, vent, floor, etc). What you need is a āblendā door actuator (hot and cold controls), if youāre having trouble with temp. They probably have different shaft sizes for the different doors. Or thatās my guess.