Jump to content

HVAC Actuators not working

E P

By E P
in Troubleshooting & Recalls

 Share

Recommended Posts

E P Enthusiast

E P

Posted
Posted

Hey everyone,

 

Parked my 2015, left for work for 6 weeks, came home and found some sort of rodent made a nest in the cabin filter. 

 

All was well, but my HVAC Actuators aren't working. I tore most of the dash apart, removed the filter, blower motor, etc to access the mess they made behind the dash and got that all cleaned up. 

 

I ordered some new actuators, plugged a new one in and the actuator itself won't work. I can move the cam with my hands and everything works and is free. 

 

All I can think of is somewhere down the circuit, the wires may have gotten chewed. But what's strange is that none of the actuators themselves seem to be working. I believe there's 3. Driver blend, passenger blend and the mode actuator located to the left behind the glove box. None will work. I've attempted to locate a fuse, changed all the ones I could find related to AC/HVAC. 

 

Anyone have any ideas where to start? I've got 60% of the dash apart, but before I commit to a full teardown I figured I'd post here and get some advice. Even a wiring diagram for the blend doors would go a long way. 

 

Thanks! 

E P Enthusiast

E P

Posted
  • Author
Posted

I couldn't find an RPO for C67 or C42. I have C49 listed in my glovebox. 

 

Tried yanking fuse 26 on the driver side interior fuse box to perform an HVAC reset, still nothing. Seems like I'm not getting any power to the actuators. 

tbarn Senior Enthusiast

tbarn

Posted
Posted

C49 is rear defrost. How about CJ2? Or better yet a VIN.

E P Enthusiast

E P

Posted
  • Author
Posted (edited)

I've found a wiring diagram, and haven't been able to find any faulty wiring. This has me scratching my head. I have power going to the HVAC control module, but the actuators aren't working. 

 

Just trying to save myself from taking off the steering column to get the dash off but I might have no choice. 

 

According to my diagram, all the actuators are tied in through the black/yellow wire and grey/red. 

 

 

Edited by E P
tbarn Senior Enthusiast

tbarn

Posted
Posted

CJ2 it is. Check for 5v, 12v and grounds per diagrams. otherwise you will probably need a scan tool and diagnostic chart.

Screenshot (28).jpg

Screenshot (29).jpg

E P Enthusiast

E P

Posted
  • Author
Posted

I ended up finding the issue after getting the dash off and tracing wires. Something chewed the wiring up right up behind the mode actuator, near the firewall. 

 

I'll probably have to yank the HVAC case to access the other end to splice it. What a nightmare. 

  • Like 1
E P Enthusiast

E P

Posted
  • Author
Posted

 3 identical black and yellow wires. I've spliced all the others, can't get the actuator behind the glovebox working.

IMG_20250305_135516115.jpg

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.3k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,716
    Total Members
    8,960
    Most Online
    BDS my HD
    Newest Member
    BDS my HD
    Joined

  • Who's Online   1 Member, 0 Anonymous, 604 Guests (See full list)

  • Latest Articles

  • Posts

    • BDS my HD
      Brand new to this forum. Questions about re-gearing my 26’ HD

      By BDS my HD · Posted

      Hello hello looking forward to expanding my knowledge of the 2026 2500 HD that I just bought.   Truck has 3500 miles on it four-wheel-drive crew cab and I’m about to put a 6 1/2 inch BDS lift on it 18 x 10 -25 offset with 37’s   Already have the wheels and tires just waiting on the lift install in about three weeks   Question what surprises am I not gonna be happy with?  I’m not new to lifted trucks so I know that acceleration towing gas mileage all that is affected..   Question is those of you that have this truck this powertrain with a 10 speed Allison and have done the mods that I’m doing,,, how bad is it? Is that Allison constantly gonna be hunting for the right gear to go into? And what about towing, acceleration, fuel consumption as mentioned?    Lastly how come I can’t find any ring pinion gear set up for these axles and when could I expect to see them?   I apologize if there’s any typos I’m doing speech to text on my iPhone.    
    • linc45bn
      2013 2500HD 6.0L intermittent no crank no start

      By linc45bn · Posted

      I've got a 2013 2500 6.0L Flexfuel. Drove the truck earlier today with no issues. Went to run an errand tonight and noticed key fob wouldn't work. Figured battery was dead, so replaced fob batter. Still wasn't working. Grabbed my other set of keys with the other fob and that one wasn't working either. So I manually unlock truck and insert key. Interior lights come on, dashboard lights up, turn key and truck starts. Turn truck off, like a moron, and try starting again. This time no crank, no click, no nothing. Lights still come on and dash lights up, but now I'm getting a service 4wheel drive, service tire monitor, etc. Check voltage on battery and Im showing 12.2v. Throw my battery charger on it and give it 15 mins and try starting again. But still no crank no start. Decide maybe its a bad battery, run to autozone grab a new one and put it in. Same issue. Disconnect battery and let it sit for 15 mins. Try again and still nothing. I had managed to roll the windows down earlier as its a humid night, but now I can't get them to roll up. Power locks are also not working now. Then randomly I try the key again, and it fires right up. Immediately I roll up the windows as we have nothing but rain forecast this week. I shut it back off wait 30 seconds and start up again. Worked a 2nd time. So turn it off, start putting things back together. Try one more time, and back to no crank no start. And now the car alarm starts going off. Had to disconnect battery and leave it that way for the night as I don't think my neighbors would appreciate my alarm going off again tonight. Any thoughts or help would be appreciated. 
    • Grumpy Bear
      first oil change - 2026 2500HD gas

      By Grumpy Bear · Posted

      No one will care for you like you care for you. Do what you can for as long as you can. IMHO of course. 
    • Grumpy Bear
      Oil Consumption

      By Grumpy Bear · Posted

      How about them NICKS!!! 
    • Peoplemvr
      GMC 1500 Illuminated Front Grill Emblem REPLACEMENT.

      By Peoplemvr · Posted

      Hi there.  Long time lurker, first post.    i have read the previous posts regarding the water ingress problem with this emblem.  I bought my 1500 SLT the  summer of 2025 new and after reading the MANY problems with these emblems failing I decided to install one anyways.  As per a YouTube video, I sealed ( or tried to) this sign with silicone sealant around the outer perimeter joint and the holes that were already somewhat sealed on the rear plate of the emblem.  And installed the connector assembly using dielectric grease on the connectors. The installation looked great and worked well for about 4 months……then FAILURE.  Grrrrrr…… I live in the great white north and wash my truck weekly in an automatic car wash  to keep the salt off.  Let me tell you that removing the old, failed emblem is a whole different animal than removing the OEM individual letters without removing the grill assembly. Mainly because the illuminated logo is built differently than the original letters which  you can remove the red surface lettering with a knife or some kind of blade which gives access to the tabs which hold the logo onto the grill. So I had to essentially destroyed the old emblem to remove it. Doing so killed my chance of doing somekind of autopsy on the failed , old logo.  But there was plenty of water inside when I ripped it apart.  Prior to installing the new assembly I tried it with the old harness and it works fine.   Does anyone have any insight as to where the water is getting into this emblem? I intend to seal the new logo with slow curing epoxy this time around using a syringe.  I think this newer emblem may be an updated unit which I hope GM got the vendor to fix. It has an October 2025 date on it.    If this one  fails,  I am just going to revert back to the non-illuminated letters….AFTER PULLING THE GRILL.    Any thoughts on sealing with epoxy would be appreciated. Thx!   Doug  

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...