Duramax Diesels Forum Truck of the Week
  #1  
Old 06-11-2019, 09:14 AM
Bdsankey's Avatar
Bdsankey Bdsankey is offline
Gearhead

 
Join Date: Feb 2018
Location: Neenah, Wisconsin
Posts: 673

Default 02 LB7 CCSB HVAC Control Panel Issues

So on drive to/from DPC 2019 I was experiencing some HVAC issues. All of a sudden while driving the A/C would just stop like it would try to switch vent positions (position wasn't touched on the control panel). You could hear air moving inside the dash (fan was loud) but not much came out of the vents even on max fan speed. We unplugged the mode control door actuator on the driver's side of the ducting thinking that somehow it was moving and causing an issue. That didn't fix the problem.





I am wondering if my HVAC control panel is acting up and just doing what it wants? It fixes itself at every single key cycle, for example if you pull over or stop for fuel and shut the truck off it will work properly for some time. Also, if you turn the HVAC off for say 30-60min and then turn it back on sometimes it works correctly sometimes it doesn't. The only sure fire fix is a key cycle.
__________________
Current Rides:
1) Toy: 2005 LLY ECSB, Leather, Sunroof
-1340hp/2200ft-lbs @ ATS Diesel (06/04/19)
-Built Motor, Tuned by Zach @ Starlite, Forced Inductions Billet ETR Gen 4 S480/96/1.10 T6 w/V2 Race Cover, Modded Exergy 250% Injectors, Exergy 14mm Street Pump/LBZ CP3, Goerend Q Converter, Billet Trans, Fuelab Supply Pump/Reg, RCD & Beans Sumps, Front E-Locker, TrueTrac, Yukon 4340 Rear Shafts, Traction Bars, DHD Center Link Brace, DHD Lower Crossmember Support


2) DD/Tow Rig: 2002 LB7 CCSB, Leather, Loaded
-Bosch NEW Injectors, FASS 150, 3" Downpipe, 4" Downpipe Back, RCD Sump, PPE Sleeves, DHD Centerlink Brace, DHD Lower Crossmember Support, Steering Wheel Radio Control Swap
Reply With Quote
  #2  
Old 06-11-2019, 10:26 AM
zakkb787's Avatar
zakkb787 zakkb787 is online now
<thatís not me...
 
Join Date: Sep 2014
Location: Granite Falls NC
Posts: 1,679

Default

I believe there are three different actuators under the dash. My dads 99 would do weird things and of course it was the hardest to get to. Might could find a cheap panel on eBay to double check, but my bet would be on one of the actuators.
__________________
2006 LLY CC/SB LT3 black, charcoal interior, tuned, leveled on 33s, my little piece of heaven

Other toys:
1982 K10 6.2 Detroit diesel/sm465/np205 with 4 inch lift and 35s.
2011 Yamaha YFZ450X
2018 GasGas XC300
Reply With Quote
  #3  
Old 06-11-2019, 12:58 PM
Bdsankey's Avatar
Bdsankey Bdsankey is offline
Gearhead

 
Join Date: Feb 2018
Location: Neenah, Wisconsin
Posts: 673

Default

Quote:
Originally Posted by zakkb787 View Post
I believe there are three different actuators under the dash. My dads 99 would do weird things and of course it was the hardest to get to. Might could find a cheap panel on eBay to double check, but my bet would be on one of the actuators.
The actuator must be told what to do is the part that boggles my mind. If it isn't being told to move it *shouldn't* move.
__________________
Current Rides:
1) Toy: 2005 LLY ECSB, Leather, Sunroof
-1340hp/2200ft-lbs @ ATS Diesel (06/04/19)
-Built Motor, Tuned by Zach @ Starlite, Forced Inductions Billet ETR Gen 4 S480/96/1.10 T6 w/V2 Race Cover, Modded Exergy 250% Injectors, Exergy 14mm Street Pump/LBZ CP3, Goerend Q Converter, Billet Trans, Fuelab Supply Pump/Reg, RCD & Beans Sumps, Front E-Locker, TrueTrac, Yukon 4340 Rear Shafts, Traction Bars, DHD Center Link Brace, DHD Lower Crossmember Support


2) DD/Tow Rig: 2002 LB7 CCSB, Leather, Loaded
-Bosch NEW Injectors, FASS 150, 3" Downpipe, 4" Downpipe Back, RCD Sump, PPE Sleeves, DHD Centerlink Brace, DHD Lower Crossmember Support, Steering Wheel Radio Control Swap
Reply With Quote
  #4  
Old 06-11-2019, 01:36 PM
JoshH's Avatar
JoshH JoshH is offline
Daggum farm truck
 
Join Date: Feb 2007
Location: Texas!!!
Posts: 13,057

Default

Is this while running the A/C only? I had an issue with my LMM when I swapped the control module, and it was programmed for an evap temp sensor instead of a low pressure switch. It wouldn't allow the compressor to cycle and the evaporator core would freeze up and act like you are describing. It would make a lot of noise, but no air would come out any of the vents. I would have to turn of the truck or A/C for a little while and let the evaporator thaw out so air could flow through it. I figured it out when I popped the hood and saw a half an inch of ice on the low pressure line running to the compressor coming out of the dryer/accumulator.
__________________
06 Silverado 4x4 CC/SB

06 Express 2500 Duramax Van "The Dumpster"


Reply With Quote
  #5  
Old 06-11-2019, 01:39 PM
Bdsankey's Avatar
Bdsankey Bdsankey is offline
Gearhead

 
Join Date: Feb 2018
Location: Neenah, Wisconsin
Posts: 673

Default

Quote:
Originally Posted by JoshH View Post
Is this while running the A/C only? I had an issue with my LMM when I swapped the control module, and it was programmed for an evap temp sensor instead of a low pressure switch. It wouldn't allow the compressor to cycle and the evaporator core would freeze up and act like you are describing. It would make a lot of noise, but no air would come out any of the vents. I would have to turn of the truck or A/C for a little while and let the evaporator thaw out so air could flow through it. I figured it out when I popped the hood and saw a half an inch of ice on the low pressure line running to the compressor coming out of the dryer/accumulator.
I believe only while the A/C is running. I haven't had that level of buildup but it also is random lengths of time. Sometimes its hours, others its a few minutes which is why I'm leaning towards a dumb electrical control issue vs a freezing evap core. I guess next time it does it I can pull the cabin air filters and look at the core.



It's got a brand new ACDelco compressor, new ACDelco receiver/drier, new ACDelco orifice tube, new ACDelco pressure switches, new off brand hoses/lines. Only part of the system not new is the evap core. It could be an evap core, I just pray to god it isn't. If I recall correctly it requires me to gut the dash to change.
__________________
Current Rides:
1) Toy: 2005 LLY ECSB, Leather, Sunroof
-1340hp/2200ft-lbs @ ATS Diesel (06/04/19)
-Built Motor, Tuned by Zach @ Starlite, Forced Inductions Billet ETR Gen 4 S480/96/1.10 T6 w/V2 Race Cover, Modded Exergy 250% Injectors, Exergy 14mm Street Pump/LBZ CP3, Goerend Q Converter, Billet Trans, Fuelab Supply Pump/Reg, RCD & Beans Sumps, Front E-Locker, TrueTrac, Yukon 4340 Rear Shafts, Traction Bars, DHD Center Link Brace, DHD Lower Crossmember Support


2) DD/Tow Rig: 2002 LB7 CCSB, Leather, Loaded
-Bosch NEW Injectors, FASS 150, 3" Downpipe, 4" Downpipe Back, RCD Sump, PPE Sleeves, DHD Centerlink Brace, DHD Lower Crossmember Support, Steering Wheel Radio Control Swap

Last edited by Bdsankey; 06-11-2019 at 01:48 PM.
Reply With Quote
  #6  
Old 06-11-2019, 03:36 PM
BlkMax's Avatar
BlkMax BlkMax is offline
Hotrodder
 
Join Date: Aug 2008
Location: Wasilla, AK
Posts: 702

Default

Can you override control of that system with a Tech II?


I know I can do it on my '04, but that one has the fancy side to side, automatic HVAC controller in the dash...
__________________
Black Max....

Black Max, the fun truck:
'03 2500 4x4 CC/LB
Bent Rods, now under construction, its time to put all the saved up parts in....
Special thanks to Pat & Kat McSwain, MikeL, Guy, Trent, and others from here-thank you for the great ideas!
EPR triples

Emma, my DD:
'04 2500 4x4 EC/SB
HTT T4 366 74 .91, 65% SAC's from LDS, 10mm CP3 from Fleece, Trans Kit from Evan, tunes by Mark at Danville
Reply With Quote
  #7  
Old 06-11-2019, 03:52 PM
DAVe3283's Avatar
DAVe3283 DAVe3283 is online now
Heavy & Slow



 
Join Date: Sep 2009
Location: Boise, ID, USA
Posts: 3,053

Default

The blend door motors have been the same since the mid-1990s on GM vehicles, and they are kind of a crappy design. It is a crappy little DC motor run through 3 sets of plastic (yes, plastic) gears to drive the output. Off one of the gears is another gear to a rotary potentiometer.

There are a few ways they fail. Older ones would crack the output socket, so the actuator would move but the blend door wouldn't. Later ones use a metal insert in the final gear to help with this. Or one of the other gears can crack, strip teeth off, etc. Then it won't be able to move where it wants, and can sometimes change temperature as a bump in the road moves the blend door and the actuator can't do anything about it. Or it just gets stuck at some position until a bump moves it past the broken teeth. Finally, the potentiometer can get worn/dirty and think the actuator is positioned somewhere it isn't. This will cause the control module to command the actuator to move towards the "correct" spot (which, of course, isn't).

If the control module commands the actuator to move (+) and sees the feedback decrease instead (due to flaky pot), it will disable the actuator for that key cycle. This sounds like what yours is doing. So if the foot/face/defrost (mode door) actuator pot flakes out, the control module will attempt to put it "back" (even though it never moved, it thinks perhaps you hit a bump, but it's just crapped out). Now it starts moving, and might suddenly report travel the wrong way (again, crappy sensor, not actually doing the wrong thing). Module freaks out, gives up, and disables that actuator, now helpfully located in some useless in-between mode sending air half to your feet half to windshield or some crap.

None of the actuators are easy to get to. The pre-03 trucks are subtly different, but on my 2003 I had to remove the dash trim entirely (which means passenger air bag, vents, etc. come off) to get to the actuators. Then the replacement BRAND NEW ACDELCO mode actuator didn't have the balls to actually change modes, and would get stuck if I tried to use defrost, so I ended up DOING IT ALL AGAIN to put the original back, since that one worked besides some random clicking noises. But I'm not bitter, no sir...


Anyway, good luck / have fun. I wish I could tell you a brand of actuator to replace them with to never have to touch them again, but as far as I can tell, they are all crap, so just get whatever is cheapest and cross your fingers.
__________________

Reply With Quote
  #8  
Old 06-11-2019, 05:16 PM
Bdsankey's Avatar
Bdsankey Bdsankey is offline
Gearhead

 
Join Date: Feb 2018
Location: Neenah, Wisconsin
Posts: 673

Default

Quote:
Originally Posted by BlkMax View Post
Can you override control of that system with a Tech II?


I know I can do it on my '04, but that one has the fancy side to side, automatic HVAC controller in the dash...
I believe a tech2/snapon will command them. I know it works on my 99 bonneville. Thatís going to be my first step before just throwing parts at it.
__________________
Current Rides:
1) Toy: 2005 LLY ECSB, Leather, Sunroof
-1340hp/2200ft-lbs @ ATS Diesel (06/04/19)
-Built Motor, Tuned by Zach @ Starlite, Forced Inductions Billet ETR Gen 4 S480/96/1.10 T6 w/V2 Race Cover, Modded Exergy 250% Injectors, Exergy 14mm Street Pump/LBZ CP3, Goerend Q Converter, Billet Trans, Fuelab Supply Pump/Reg, RCD & Beans Sumps, Front E-Locker, TrueTrac, Yukon 4340 Rear Shafts, Traction Bars, DHD Center Link Brace, DHD Lower Crossmember Support


2) DD/Tow Rig: 2002 LB7 CCSB, Leather, Loaded
-Bosch NEW Injectors, FASS 150, 3" Downpipe, 4" Downpipe Back, RCD Sump, PPE Sleeves, DHD Centerlink Brace, DHD Lower Crossmember Support, Steering Wheel Radio Control Swap
Reply With Quote
  #9  
Old 06-11-2019, 05:18 PM
Bdsankey's Avatar
Bdsankey Bdsankey is offline
Gearhead

 
Join Date: Feb 2018
Location: Neenah, Wisconsin
Posts: 673

Default

Quote:
Originally Posted by DAVe3283 View Post
The blend door motors have been the same since the mid-1990s on GM vehicles, and they are kind of a crappy design. It is a crappy little DC motor run through 3 sets of plastic (yes, plastic) gears to drive the output. Off one of the gears is another gear to a rotary potentiometer.

There are a few ways they fail. Older ones would crack the output socket, so the actuator would move but the blend door wouldn't. Later ones use a metal insert in the final gear to help with this. Or one of the other gears can crack, strip teeth off, etc. Then it won't be able to move where it wants, and can sometimes change temperature as a bump in the road moves the blend door and the actuator can't do anything about it. Or it just gets stuck at some position until a bump moves it past the broken teeth. Finally, the potentiometer can get worn/dirty and think the actuator is positioned somewhere it isn't. This will cause the control module to command the actuator to move towards the "correct" spot (which, of course, isn't).

If the control module commands the actuator to move (+) and sees the feedback decrease instead (due to flaky pot), it will disable the actuator for that key cycle. This sounds like what yours is doing. So if the foot/face/defrost (mode door) actuator pot flakes out, the control module will attempt to put it "back" (even though it never moved, it thinks perhaps you hit a bump, but it's just crapped out). Now it starts moving, and might suddenly report travel the wrong way (again, crappy sensor, not actually doing the wrong thing). Module freaks out, gives up, and disables that actuator, now helpfully located in some useless in-between mode sending air half to your feet half to windshield or some crap.

None of the actuators are easy to get to. The pre-03 trucks are subtly different, but on my 2003 I had to remove the dash trim entirely (which means passenger air bag, vents, etc. come off) to get to the actuators. Then the replacement BRAND NEW ACDELCO mode actuator didn't have the balls to actually change modes, and would get stuck if I tried to use defrost, so I ended up DOING IT ALL AGAIN to put the original back, since that one worked besides some random clicking noises. But I'm not bitter, no sir...


Anyway, good luck / have fun. I wish I could tell you a brand of actuator to replace them with to never have to touch them again, but as far as I can tell, they are all crap, so just get whatever is cheapest and cross your fingers.
Thanks for the info. Itís like it just randomly loses the ability to move air even with the mode door unplugged which leads me to a recirc door issue or control issue. If I can command it to do what I want via a tech2/snapon to me that would point towards a heater panel.



I donít believe the 2002 trucks have a cabin sensor that it used to read off of. Mine just has the hot/cold dial without any temp numbers on it.
__________________
Current Rides:
1) Toy: 2005 LLY ECSB, Leather, Sunroof
-1340hp/2200ft-lbs @ ATS Diesel (06/04/19)
-Built Motor, Tuned by Zach @ Starlite, Forced Inductions Billet ETR Gen 4 S480/96/1.10 T6 w/V2 Race Cover, Modded Exergy 250% Injectors, Exergy 14mm Street Pump/LBZ CP3, Goerend Q Converter, Billet Trans, Fuelab Supply Pump/Reg, RCD & Beans Sumps, Front E-Locker, TrueTrac, Yukon 4340 Rear Shafts, Traction Bars, DHD Center Link Brace, DHD Lower Crossmember Support


2) DD/Tow Rig: 2002 LB7 CCSB, Leather, Loaded
-Bosch NEW Injectors, FASS 150, 3" Downpipe, 4" Downpipe Back, RCD Sump, PPE Sleeves, DHD Centerlink Brace, DHD Lower Crossmember Support, Steering Wheel Radio Control Swap
Reply With Quote
  #10  
Old 06-12-2019, 07:22 AM
JoshH's Avatar
JoshH JoshH is offline
Daggum farm truck
 
Join Date: Feb 2007
Location: Texas!!!
Posts: 13,057

Default

It has been a little while since I tore into the HVAC housing, but the best I can remember, there is no way for the actuator to move and completely block flow through the vents. It will either come out the floor, dash, or defrost in some combination.
__________________
06 Silverado 4x4 CC/SB

06 Express 2500 Duramax Van "The Dumpster"


Reply With Quote
  #11  
Old 06-12-2019, 07:31 AM
Bdsankey's Avatar
Bdsankey Bdsankey is offline
Gearhead

 
Join Date: Feb 2018
Location: Neenah, Wisconsin
Posts: 673

Default

Quote:
Originally Posted by JoshH View Post
It has been a little while since I tore into the HVAC housing, but the best I can remember, there is no way for the actuator to move and completely block flow through the vents. It will either come out the floor, dash, or defrost in some combination.
I should be more specific, it doesn't 100% block flow. There is very very very little airflow out the upper vents, less coming out the floor, and even less out of defrost.
__________________
Current Rides:
1) Toy: 2005 LLY ECSB, Leather, Sunroof
-1340hp/2200ft-lbs @ ATS Diesel (06/04/19)
-Built Motor, Tuned by Zach @ Starlite, Forced Inductions Billet ETR Gen 4 S480/96/1.10 T6 w/V2 Race Cover, Modded Exergy 250% Injectors, Exergy 14mm Street Pump/LBZ CP3, Goerend Q Converter, Billet Trans, Fuelab Supply Pump/Reg, RCD & Beans Sumps, Front E-Locker, TrueTrac, Yukon 4340 Rear Shafts, Traction Bars, DHD Center Link Brace, DHD Lower Crossmember Support


2) DD/Tow Rig: 2002 LB7 CCSB, Leather, Loaded
-Bosch NEW Injectors, FASS 150, 3" Downpipe, 4" Downpipe Back, RCD Sump, PPE Sleeves, DHD Centerlink Brace, DHD Lower Crossmember Support, Steering Wheel Radio Control Swap
Reply With Quote
  #12  
Old 06-12-2019, 07:38 AM
JoshH's Avatar
JoshH JoshH is offline
Daggum farm truck
 
Join Date: Feb 2007
Location: Texas!!!
Posts: 13,057

Default

There is only one actuator that moves the doors to divert air through all three outlets. It is impossible to have dash vents and defrost vents open at the same time because of how it is configured. The air flow you're feeling out of the floor and defrost are probably just leakage around the doors. I still think you have something blocking airflow. If it isn't the evap core freezing up, then there must be something in there covering it. I would hook up some A/C gauges and watch pressures to verify proper compressor cycling.
__________________
06 Silverado 4x4 CC/SB

06 Express 2500 Duramax Van "The Dumpster"


Reply With Quote
  #13  
Old 06-12-2019, 07:44 AM
Bdsankey's Avatar
Bdsankey Bdsankey is offline
Gearhead

 
Join Date: Feb 2018
Location: Neenah, Wisconsin
Posts: 673

Default

Quote:
Originally Posted by JoshH View Post
There is only one actuator that moves the doors to divert air through all three outlets. It is impossible to have dash vents and defrost vents open at the same time because of how it is configured. The air flow you're feeling out of the floor and defrost are probably just leakage around the doors. I still think you have something blocking airflow. If it isn't the evap core freezing up, then there must be something in there covering it. I would hook up some A/C gauges and watch pressures to verify proper compressor cycling.
That I have done, compressor cycling is correct. I don't recall exactly what PSI but it was within spec according to Mitchell1 as I checked that before we left (8hrs before we left and freon hadn't been added since the refill after changing a fitting).






Guess its time for the dash to come apart to change all the actuators/evap core/heater core/clean the box.
__________________
Current Rides:
1) Toy: 2005 LLY ECSB, Leather, Sunroof
-1340hp/2200ft-lbs @ ATS Diesel (06/04/19)
-Built Motor, Tuned by Zach @ Starlite, Forced Inductions Billet ETR Gen 4 S480/96/1.10 T6 w/V2 Race Cover, Modded Exergy 250% Injectors, Exergy 14mm Street Pump/LBZ CP3, Goerend Q Converter, Billet Trans, Fuelab Supply Pump/Reg, RCD & Beans Sumps, Front E-Locker, TrueTrac, Yukon 4340 Rear Shafts, Traction Bars, DHD Center Link Brace, DHD Lower Crossmember Support


2) DD/Tow Rig: 2002 LB7 CCSB, Leather, Loaded
-Bosch NEW Injectors, FASS 150, 3" Downpipe, 4" Downpipe Back, RCD Sump, PPE Sleeves, DHD Centerlink Brace, DHD Lower Crossmember Support, Steering Wheel Radio Control Swap
Reply With Quote
  #14  
Old 06-12-2019, 08:12 AM
Chevy1925's Avatar
Chevy1925 Chevy1925 is online now
don't know sh!t about IFS

 
Join Date: Oct 2009
Location: Phoenix Az
Posts: 15,535

Default

did the cabin air filters come apart?
__________________
Quote:
Originally Posted by JoshH View Post
Mike L is my role model. I want to be like him when I grow up.
James

02 LB7, LLY, LBZ, LMM, LML, L5P 2500HD CC/LB dmax/alli "The Limo"

BIG THANKS TO: Mike L, Steve, Trent, Guy, Dan, Ruben, Josh H, Scott, Brian and everyone else who has put a hand in to help me.

best time to date: 12.39

motor died/bent rods = 3/11/11
back from the dead 7:04pm 4/9/2012

Limo is back in the garage, now driving a built chevy tracker
Tailgate Crew Member #4
Reply With Quote
  #15  
Old 06-12-2019, 08:15 AM
Bdsankey's Avatar
Bdsankey Bdsankey is offline
Gearhead

 
Join Date: Feb 2018
Location: Neenah, Wisconsin
Posts: 673

Default

Quote:
Originally Posted by Chevy1925 View Post
did the cabin air filters come apart?
It's possible but I recently changed them with Denso carbon filters under 2 months ago.
__________________
Current Rides:
1) Toy: 2005 LLY ECSB, Leather, Sunroof
-1340hp/2200ft-lbs @ ATS Diesel (06/04/19)
-Built Motor, Tuned by Zach @ Starlite, Forced Inductions Billet ETR Gen 4 S480/96/1.10 T6 w/V2 Race Cover, Modded Exergy 250% Injectors, Exergy 14mm Street Pump/LBZ CP3, Goerend Q Converter, Billet Trans, Fuelab Supply Pump/Reg, RCD & Beans Sumps, Front E-Locker, TrueTrac, Yukon 4340 Rear Shafts, Traction Bars, DHD Center Link Brace, DHD Lower Crossmember Support


2) DD/Tow Rig: 2002 LB7 CCSB, Leather, Loaded
-Bosch NEW Injectors, FASS 150, 3" Downpipe, 4" Downpipe Back, RCD Sump, PPE Sleeves, DHD Centerlink Brace, DHD Lower Crossmember Support, Steering Wheel Radio Control Swap
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 04:53 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
vB.Sponsors