Problem with rear heat after replacing controller

[Red Rider]

Ok, Just replaced the controller PN 15832319, (replacing the OEM 15185966) at the rear of my 2004 tahoe. I had pulled off the actuators (both 52402599) since i was trying to trouble shoot it all but have been unable to put them back on since they are not centered (they seem to be at the zero point)

I tried following to reset computer, but it did not work for me:

1. pulling the 60amp and 10amp (i think) AC fuses under the hood
2. starting truck and idling for 1 min.
3. Turn off truck.
4. put fuses back in.
5. turn on vehicle. wait 1 min.
During procedure, HVAC is off front and back.

Actuators do nothing. Both actuators do not spin freely so from what i read, they should be ok. I took one apart and everything seemed fine inside. One moved a little with the old controller but could not get it to move again so I ordered the new controller. Can anyone give me more advice what to look at for actuators?

I read following; anyone try this?

CENTERING ACTUATORS:
"the actuator may have been over traveled. Try centering the actuator.with the key on and the connector connected, jump the yellow and white/black wires. If it doesn't move jump the white/black to gray wire. When the actuator centers have someone ready to turn the key off." http://www.fullsizechevy.com/forum/...e-rear-air-has-no-heat-just-blowing-cold.html Post 12

I have read about disconnecting battery and will try this next. Anyone have ideas, please let me know.

Frustrated....

 

[YukonXL04]

This probably isn't the case for you. But my rear heat wasn't working and it ended up being because the coolant level was low lol

 

[Red Rider]

I get heat back there and it is hot if I open blend door. Fan works.


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---------- Post added at 04:39 PM ---------- Previous post was at 03:35 PM ----------

Ok, I finally got the actuators to move. I disconnected the battery, waited a minute, reconnected the battery, turn the key to the on position (not run position), back to off, waited 10 seconds, then started the car. Then the actuators actually moved back-and-forth, but went back to the zero position that does not allow me to install them. to the actuators actually have to be installed so that they can figure out what the new zero is? Is this what recalibrating is? if so then I will have to open them up and put them to a middle position so that I can install them.

 

[Red Rider]

So I finally figured out how to reset/recalibrate the actuators. Here were the exact steps I took. (These are mostly copied from another post, i just clarified them).

The actuators NEED to be installed before you do this step. I had them hanging and it will not work. Since they had zeroed out (The little notch went all the way up if you are looking at the rear actuators installed), i could not install them. I took them apart by sliding a small flat head screwdriver under the 5 or so release tabs. Carefully lift the top gear and rotate the big black gear/wheel (this is the gear the turns the door). If it is more or less centered, you should be able to slip it on the shaft and install them. The centered location is indicated my centering marks, or longest lines on housing (see pics below.)

NOTE: IF YOU HAVE JUST BOUGHT NEW ACTUATORS, OPENING THEM UP MAY VOID THE WARRANTY. I would imagine they come centered from factory so make sure you completely install them BEFORE you try the calibration.

The actuators need to be installed because in the process of calibration, the computer opens and closes each damper (door) and figures out the minimum and maximum range at each actuator. When i had them hanging (not installed but plugged in), they would try to calibrate but i guess the computer must of thought there was an error and went to a default position and they did not work when HVAC system was turned on or settings changed.

Here are the steps for calibration for rear (i assume it would be same for front):

1. Disconnect the battery for about a minute.
2. Reconnect battery
3. Turn the ignition to the ON position for at 1-2 minutes. This is the ON position or first position, NOT the RUN position or second position (I made this mistake). On the ON position, the HVAC system should not turn on. So it does not matter if you left HVAC system on front or rear.
4. Turn the ignition to the OFF position for at least 10 seconds. Key can stay in the ignition.
5. Start the engine and confirm the actuators are working correctly by turning the climate knob from cold to hot and from low air, mixed, and high.
6. Have yourself a nice cold beer while the wife praises your status as mechanical genius. (This last step is critical so don't skip it!)

I had previously tried the pulling fuse trick that many describe. The problem is that there are a half dozen fuses labeled AC and various posts describe pulling different ones. One described pulling all the AC fuses but I did not try this. The manual does not describe what each fuse controls and I did not get a chance to look in FSM.

From some reason, the rear actuator (hot/cold) was not working. I swapped it with the high/low blend actuator and reset it again and it started working.

Here is a picture of the actuator opened up. See the raised black part on black gear? This is the part that hits the two bump stop that you see in the cover on the right (you only see one in my picture). When installed and calibrated, the raised black part will probably not hit the stops. While you have this open, you can move some of the grease that flung off the gears back onto the gears; but I can't imagine these gears ever wearing down. Be careful NOT to touch any of the electronics with fingers or screwdriver or other tools to prevent damage.

Pic of the gear i lifted up to allow the black gear to be centered. This top gear may rotate as you turn the black gear, but should not matter. make sure it is properly seated before reassembling. See that here, the black gear is repositioned in the center position. This will allow you to reinstall the actuator.

Picture of actuator how it was prior to moving the gear. This is what happened when it calibrated without being installed on the blend doors (so not being able to sense a min and max setting). The notch show the location of the raised black part that hits the stops on the actuator. the longest mark or centering mark on cover is where you want it to be (more or less) to allow for installation.

 

[cashotgun]

Red Rider was it just your heat or did the rear air not work either? I have an 03 Yukon and my rear air cuts on but it does not blow cold air. And I am trying to figure out the issue.

 

[Red Rider]

My issue was that it was blowing but it was always cold. so blend door was closed. The heater core was getting hot, but it was not getting through to the ducts. I don't remember if the other actuator was working but knew i had to deal with it anyway so started taking things apart. If by air, you mean AC, then I would imagine it would work since it was stuck to cold.

System seems to constantly regulate the doors to adjust the temperature according to sensors that calculate air temp in the ducts. It is way more sophisticated than I ever had in my other vehicles. So if one actuator is not working, you are not going to be happy, or not have happy occupants as it will either be too cold or too hot.

 

[Red Rider]

Just wanted to add... My gas gauge that has been acting weird and moving to random locations, or not lining up with the gauge marks; but still sweeps to give a rough idea of how much fuel i have left. I suspect a bad stepper motor. After a did the calibration, It was working perfectly for about a day or two. Then went back to doing the random thing. Funny.

 

[chevync]

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Is this how it's suppose to be lined up? This was the part # 604-106 that came up when I orignally bought the new one, took it to the shop not knowing about the relearn and we turned the key on without it installed and turned it to cold/hot a few times and it moved but not much, then the shop said it needed part # 604-101, we put it in, and still nothing, so I checked the arrows and noticed the 106 part wasn't lined up, so I lined them up and i'm going to try in the morning to put it back in and try the relearn again. Now when I installed the 101 part number today I made the mistake and turned the key to the run position and it didn't work, when i got home i've unhooked the battery a few times and tried your relearn and it seems worse, so i guess when i had it in the run position I moved the arrow.

 

[Red Rider]

Yes. that is the centered position. The issue is if it is at zero, then you can not put blend door on, then install actuators. Think of it this way. Actuator goes from zero to 100. The blend door, when installed, goes from 35 to 75 for example. the Programing allows vehicle to go from the min., 35, to the max., 75.

When not installed, the computer went from 0 to 100 and noticed that something is wrong so went to zero position. I could not install the blend door with actuator since bolts were not aligning.

When at or near middle, or within the min/max range, it should be able to be installed. I do not think many people come across this. It just happened to me since I was trying to see if actuators were working before putting whole thing back together and you can;t do this (or computer does not allow you to).

 

[treehan77]

thanks this reset procedure fixed my issue after replacing the control module. i guessed that was the problem because i could neither switch rear air from hot to cold nor from ceiling to floor, and i figured it was unlikely neither actuator worked. after resetting, all is well.