"Mode" door actuator issues - SOLVED

[88lance]

2002 Tahoe, doesn't have the auto climate control, just the basic normal one.

AC got stuck on defrost, so that would be the mode door actuator above the brake pedal.

Took it out, put the new one in, and all the controls were backwards. So I slid it off, and (This is apparently where I messed up) flipped the dash controls from vent to defrost, so that the hole turned, and then put it back on.

Then it was dead.

Took it off (after I found out where I screwed up) and take it back to O'Reilly's and swapped it for another one.

Made sure to not touch controls and just slide it on correctly the first time.

Plugged it in after mounting, and as soon as I plugged it in, I guess it went to whatever position the dash controller was on, because it moved a couple inches soon as I plugged it in. Then when I moved the dash controller to a different setting, it was dead. Idk how I killed it, I didn't plug it in until it was mounted.

So I don't know what I'm doing wrong, but this thing is a serious pita to remove and get back on, so I was hoping for some advice before I try it again, if anyone knows what I'm doing wrong here.

I may just take it to the shop and let someone else deal with it, unless there's something obvious that I'm doing thats killing it.

 

[justirv]

2002 Tahoe, doesn't have the auto climate control, just the basic normal one.

AC got stuck on defrost, so that would be the mode door actuator above the brake pedal.

Took it out, put the new one in, and all the controls were backwards. So I slid it off, and (This is apparently where I messed up) flipped the dash controls from vent to defrost, so that the hole turned, and then put it back on.

Then it was dead.

Took it off (after I found out where I screwed up) and take it back to O'Reilly's and swapped it for another one.

Made sure to not touch controls and just slide it on correctly the first time.

Plugged it in after mounting, and as soon as I plugged it in, I guess it went to whatever position the dash controller was on, because it moved a couple inches soon as I plugged it in. Then when I moved the dash controller to a different setting, it was dead. Idk how I killed it, I didn't plug it in until it was mounted.

So I don't know what I'm doing wrong, but this thing is a serious pita to remove and get back on, so I was hoping for some advice before I try it again, if anyone knows what I'm doing wrong here.

I may just take it to the shop and let someone else deal with it, unless there's something obvious that I'm doing thats killing it.

There is definitely some black magic needed for these that may not be readily published. IIRC, before attempting the swap, ensure all hvac controls are off. Pull the batt negative, remove mode door actuator. Physically (gently) manipulate the door to full travel both directions, checking for obstruction. Finish with door centered, match actuator drive to door spindle. Complete installation of actauator with hardware and wiring connector. Then, bring batt (neg) back online. Turn on ignition without starting engine (Key ON, Engine OFF), then WAIT at least 5 mins. You'll hear all the actuators go thru their self-test determining limits and travel. If you have followed this process with no success, you may have a control module issue. Others here will chime in shortly.

 

[88lance]

There is definitely some black magic needed for these that may not be readily published. IIRC, before attempting the swap, ensure all hvac controls are off. Pull the batt negative, remove mode door actuator. Physically (gently) manipulate the door to full travel both directions, checking for obstruction. Finish with door centered, match actuator drive to door spindle. Complete installation of actauator with hardware and wiring connector. Then, bring batt (neg) back online. Turn on ignition without starting engine (Key ON, Engine OFF), then WAIT at least 5 mins. You'll hear all the actuators go thru their self-test determining limits and travel. If you have followed this process with no success, you may have a control module issue. Others here will chime in shortly.

Thanks for the reply, I definitely missed a lot of steps then.

 

[88lance]

Just did the process with the disconnected battery and recalibration.
When I turn to the key to the on position the door moved about a quarter of a turn and made a pop sound and never moved again. Nothing made any more noises. I waited the 5 minutes and then turned the key off and waited a few more minutes and started the truck afterwards. It's completely dead again.
I don't know what the pop sound was, but I had everything moving freely and all the gears working manually before I slid the actuator on.
At this point I don't know what to do with it.

 

[88lance]

Found another part from O'Reilly's that looked exactly the same, but with a different part number. Repeated the swap for the 4th time, but noticed this time that the position the actuator is in when it comes out of the box, is floor mode.
So I manually set the door under the dash to floor mode.
Unplug battery, put the new actuator on, plugged in, reconnect battery about 8 minutes later, and turned key on the on position.

It moved about 1", looking like it was making I minor adjustment to match the dash controller.

Let it sit for a few minutes, and nothing else moved. So I slightly moved the dash controller, and it slightly moved also towards defrost.

(Feeling excited, it didn't automatically self-destruct right away).

Moved the controller on the dash a little more, and boom, it goes all the way to defrost, and kills itself.

Back to square one

 

[Fless]

The actuators aren't usually interchangeable; one part number is for a specific position, and using a different one can create issues. It's best to know which one is required in the position that's having the issue, and use that actuator.

A good bidirectional scan tool would help diagnose this, and would tell you what the commanded position is vs. the actual position. The control head might be causing it. It's just hard to tell without some scan tool data.

 

[88lance]

The actuators aren't usually interchangeable; one part number is for a specific position, and using a different one can create issues. It's best to know which one is required in the position that's having the issue, and use that actuator.

A good bidirectional scan tool would help diagnose this, and would tell you what the commanded position is vs. the actual position. The control head might be causing it. It's just hard to tell without some scan tool data.

I will probably drop it off at the shop early in the week and let them deal with it. It's unfortunate that it couldn't be a simple cheap part swap, but it's starting to look like it's a deeper issue

 

[swathdiver]

I will probably drop it off at the shop early in the week and let them deal with it. It's unfortunate that it couldn't be a simple cheap part swap, but it's starting to look like it's a deeper issue

There's a thread on here that lists the locations of guys with Tech-2s that are willing to help folks who need access to one. Check and see if anyone on here lives near you.

 

[88lance]

There's a thread on here that lists the locations of guys with Tech-2s that are willing to help folks who need access to one. Check and see if anyone on here lives near you.

Nice, where do I find the thread that has the list?

 

[swathdiver]

Nice, where do I find the thread that has the list?

Search for it I guess...

Tech 2 Owners Map

There are quite a few members that have a Tech 2 and there are always people who wish they had one to use so I thought I would post this thread to try and help each other out. If you own a Tech 2 and would be willing to help out another forum member that might be local to you then post up your...

www.tahoeyukonforum.com

Someone updated it today.

 

[88lance]

Is it possible for the head control unit on the dash to be the problem?

I did some research and it mentioned how the actuator is given a voltage signal, and different levels of voltage tell the actuator what position to move to, ranging from 0V to 5V.

It didn't say what voltage is what position, but considering it directly flips to defrost and never does anything else afterwards, it makes me wonder if "defrost" is "0V", and if the head unit IS what controls that, and quit working, then the actuator would go to exactly that point, 0V. (If that's defrost).

What I'm unsure of is whether that voltage is actually controlled by the head unit itself, or whether that's a completely different part in the dash somewhere.

 

[Fless]

Is it possible for the head control unit on the dash to be the problem?

What I'm unsure of is whether that voltage is actually controlled by the head unit itself, or whether that's a completely different part in the dash somewhere.

Yes to #1. The HVAC control module (head unit) sends the 5v and varied control signals. See CHARM link below.

CHARM Link

 

[88lance]

Yes to #1. The HVAC control module (head unit) sends the 5v and varied control signals. See CHARM link below.

CHARM Link

Great, thanks! Wrecking yard tomorrow to plug in a different head unit then, we'll see what happens.

 

[88lance]

Well, new head unit doesn't fix it, so back to square one. Probably just going to have to bring it to someone at this point

 

[88lance]

Update just in case anyone else runs into this. Mechanic shop tried a different head unit also, didn't work.
They tested voltage to everything, it all checked out.
They put the new actuator on I had bought, it turned some but then quit working just like all the rest.
They went and bought an actual GM actuator and put it on....and it works.

That's 5 (I think?) actuators from O'Reilly's, trying two different part numbers that both fit.

Final verdict from the mechanic, the aftermarket actuators were not strong enough to open and close the doors enough to hit the "end stops" when it was relearning it's limits, and stalled out. (Not sure whether that means it broke it, or whether that means it just turned off like a breaker or something). OEM is much stronger and was able to push the doors to each full open/close mode, learning it's limits, calibrating itself, and works perfectly.

One of those things that it just pays to pay the price for OEM apparently. Just glad to have my Tahoe back. Haha

 

[justirv]

Update just in case anyone else runs into this. Mechanic shop tried a different head unit also, didn't work.
They tested voltage to everything, it all checked out.
They put the new actuator on I had bought, it turned some but then quit working just like all the rest.
They went and bought an actual GM actuator and put it on....and it works.

That's 5 (I think?) actuators from O'Reilly's, trying two different part numbers that both fit.

Final verdict from the mechanic, the aftermarket actuators were not strong enough to open and close the doors enough to hit the "end stops" when it was relearning it's limits, and stalled out. (Not sure whether that means it broke it, or whether that means it just turned off like a breaker or something). OEM is much stronger and was able to push the doors to each full open/close mode, learning it's limits, calibrating itself, and works perfectly.

One of those things that it just pays to pay the price for OEM apparently. Just glad to have my Tahoe back. Haha

Thanks so much for closing the loop, happy that you got it resolved, and appreciate the added info. Mine may be acting up on me now

 

[88lance]

Thanks so much for closing the loop, happy that you got it resolved, and appreciate the added info. Mine may be acting up on me now

Let us know what happens

 

[swathdiver]

Glad you got it solved. Aftermarket actuators don't work well in these trucks for some reason. Cross that one off your gripe sheet and onto the next!