Chevy Silverado and GMC Sierra Forum banner
1 - 13 of 13 Posts

·
Registered
2005 Sierra 1500 SLE Z71 L33
Joined
·
27 Posts
Discussion Starter · #1 ·
When I set the air in my truck to just the upper vents, everything is fine. If I put it to the dual one for legs and body, then the air also comes out through the defrost vents, also if I put it on just legs only. It gets annoying because at night or on a cooler day it’ll fog up my side windows. Do I need a new mode actuator or is this normal? I hear the grinding of that motor every time the truck starts for the first time of the day, then it stops after a second.
 

·
Registered
Joined
·
824 Posts
Time for a new mode actuator. It's the one in the driver's footwell.
 

·
Registered
2005 Sierra 1500 SLE Z71 L33
Joined
·
27 Posts
Discussion Starter · #4 ·
So I did the replacement, and it’s still exactly the same, just not as noisy. The air is set to feet, but I still feel it come out of the side defrost along with feet. It creates very weak flow when I want to to just feet or to body and feet because it comes out the side defroster as well. Any ideas to what this could be? Maybe some input from other guys with these trucks.
 

·
Registered
2004 Sierra 3500 6.0L, auto, extended cab, cab&chassis, upgraded to 4wd
Joined
·
1,687 Posts
Maybe first visually watch that the cam moves through the full range when you change through the modes (yes, it's difficult to see, maybe make a video using your phone and watch how it moves afterwards).

If it does move through the whole range, then I would remove the actuator and cam, and then feel how the lever's move by hand, that the cam operates on (it's possible for the arm to fail or something to prevent it from moving all the way).

You might also find this video useful/helpful:
 

·
Registered
Joined
·
824 Posts
Did you re-calibrate all the actuators? There is way to do it manually but such has never worked for me, I always use the scan tool. Hopefully more will chime in!
 

·
Registered
2005 Sierra 1500 SLE Z71 L33
Joined
·
27 Posts
Discussion Starter · #7 ·
Did you re-calibrate all the actuators? There is way to do it manually but such has never worked for me, I always use the scan tool. Hopefully more will chime in!
I pulled the power to the unit for a few minutes then plugged it back in and the doors went everywhere for a little bit (I didn’t touch controls) then it was still doing the same thing where air comes out from the side defrost on any mode with the feet in it.
 

·
Registered
2005 Sierra 1500 SLE Z71 L33
Joined
·
27 Posts
Discussion Starter · #8 ·
Maybe first visually watch that the cam moves through the full range when you change through the modes (yes, it's difficult to see, maybe make a video using your phone and watch how it moves afterwards).

If it does move through the whole range, then I would remove the actuator and cam, and then feel how the lever's move by hand, that the cam operates on (it's possible for the arm to fail or something to prevent it from moving all the way).

You might also find this video useful/helpful:
Yeah so it’s starting to sound like the foam on the inside is just trashed for me too. You know how the vents all have that slider to block the flow except that one next to the radio? Yeah the foam for all those has been gone for years now so they don’t seal at all whenever you spin the slider. Unfortunate, but it’s an almost 18 year old non-garage kept Texas truck. It’s seen it’s fair share of heat so probably just nothing to do at this point.
 

·
Registered
Joined
·
824 Posts
You're going to want to put a Tech-2 on it and check the internal BCM codes and use it to perform diagnostics. Could be the controller then but I'm just speculating from my chair over here. Live in Florida by chance? I'm in Port Saint Lucie and have a Tech-2.
 

·
Registered
2005 Sierra 1500 SLE Z71 L33
Joined
·
27 Posts
Discussion Starter · #10 ·
You're going to want to put a Tech-2 on it and check the internal BCM codes and use it to perform diagnostics. Could be the controller then but I'm just speculating from my chair over here. Live in Florida by chance? I'm in Port Saint Lucie and have a Tech-2.
All the way in Texas lol… wish I could get my hands on one of those Tech 2s.
 

·
Registered
Joined
·
824 Posts
All the way in Texas lol… wish I could get my hands on one of those Tech 2s.
New ones are about $300 and pay for themselves in no time. We can't effectively diagnose or work on these three generations of trucks without it. (GMT400, 800, 900)
 

·
Registered
Joined
·
824 Posts
Where can they be bought from?
Sometimes you can find used ones on local apps like OfferUp and CraigsList. New and used on Ebay but most of them come from China where they are made, ChinaCarDiags has a good reputation. The important thing is to choose a seller with lots of good reviews. Get one with all the little adapters and accessories which are used to power it in various ways and for self-tests. Make sure the PCMCIA card has the 33.004 software. It's fairly intuitive to use one, I have no formal training, just bought one and started using it.
 
1 - 13 of 13 Posts
Top