Heater blasting on one side, vent air on the other

[Shdwdrgn]

2004 Trailblazer SWB, I had the battery disconnected on Sunday to repair my horn, and it's taken me a couple days to realize I'm now having a problem with my climate control. Basically I'm getting cool air vent on the driver's side as expected, but the passenger side is blowing really hot air. On the dash control, the driver's side is set to 68, and I set the passenger's side down to 60 but it won't stop blowing the heat. It was 60° on my way home yesterday and it took most of the drive to finally realize where all the hot air was coming from since I could feel the cool air coming from my vents. Oh, and if this matters, the hot air is blowing from the dash vents, not from the floor where it normally comes from.

Anyone seen this happen before? I'm thinking it might be worthwhile today to pull the battery again just to try and reset the controls as this has never happened before, but maybe there's a fuse I can pull to do the same task without having to reset everything else? I'm just not sure where to even begin troubleshooting this.

 

[Mooseman]

There is a fuse. Pull the HVAC-B fuse for about 10 seconds, put it back, turn the key to RUN but don't start, don't touch HVAC controls while it calibrates the actuators. Should just be a couple minutes.

If it's still not working, then likely the passenger temp actuator has left the chat.

J

Thread 'a/c control issues 2005 TB'

Sep 11, 2012

I have a 2005 TB LT with electronic dual climate control. I have noticed some intermittent problems with mode and temperature control. I've been reading a bit on the Trailvoy forum and while there is some good if scary info it seems to deal mostly with models even older than mine. Is there a systematic method for diagnosing and addressing problems with the various actuator components in the system. Unlike most folks, my system seems to function properly in the a/c mode, but when heat is called for it is hit or miss what or where it will come from. Tks in advance.

• jaktomas1
• Replies: 12
• Forum: Technical Discussion

To replace it, you might have to cut part of the bracket that's in front of it. Post #3 talks about it:

D

Thread 'hvac actuators and dash removal'

Mar 2, 2012

Well it looks like mt passenger temp door acuator is going. I already replaced the dash / floor one but it needs mor adjustment.

I removed my dash from my dodge truck once and found it to be easyier than I expected. I know you don't have to do it but would it make it alot easier to do the repairs.

Any good resources with that info in it.

• dcbenvoy
• Replies: 83
• Forum: Technical Discussion

 

[Shdwdrgn]

Thanks for that! Just pulled the fuse to reset the system, everything came back up reset to 72 degrees so it looks promising. I won't be driving anywhere else until Saturday though so I won't know if this was successful until I get the engine warmed up again.

And oh god, I really hope it doesn't come down to fixing that actuator. I had to do that once on a '97 Blazer, that quite the project. I think I'd rather tear down the front end again instead of that! Would something as simple as disconnecting the battery really cause that to fail though?

 

[Mooseman]

It's not the fact you disconnected the battery, it's because it was probably on its last legs and was destined to fail due to age as the plastic gears inside crack. When the battery is disconnected, it goes through the full range of the actuator to do the relearn, thus, precipitating the actuator to fail. It would have eventually failed on its own at the worst time.

 

[Shdwdrgn]

Ugh bad news... Went out shopping today and it's still pumping hot air out the passenger side. And here I thought I was finally catching up on problems. Guess I'll be looking over those links later to see just how bad this is going to be. In my case, you can feel the stark contrast from the center vents on the dash above the controls -- cold from the left vent and hot from the right vent. Nothing seems to be blowing from the floor so it just seems the be the mixer for that side causing the problem.

 

[Mooseman]

Looks like you have two issues going on; the Temp actuator on the passenger side and the floor/dash actuator. The passenger one will give you the most grief as there is a metal bracket in its way. Some have been able to cut part of it to be able to pull the actuator. Thanks GM engineers

 

[Shdwdrgn]

I haven't actually played with the controls yet to make sure it's still switching between the vent modes. It's blowing from the central dash because that's where it's supposed to be for the current conditions -- my side is correctly blowing cooler outside air. I always assumed there was a single control for which vents the air was blowing out of that controlled both sides together? The passenger side also *thinks* it is blowing cooler air, so the dash ducts would be the correct location for that to come out of.

 

[Mooseman]

my side is correctly blowing cooler outside air. I always assumed there was a single control for which vents the air was blowing out of that controlled both sides together?

That is correct. It is a single door/actuator for dash/floor and another single one for switching to defrost. It's only temperatures that are individual to each side.

 

[Shdwdrgn]

Reading through the second link of yours, it looks like I was already there 9 years ago! Sheesh I don't even remember doing that but it must have been one of the easy ones I replaced at that point. Now this one on the passenger side seems like a real bear.

So I saw Roadie's pics with the entire dash removed but that sounds more like a 2-person job that I'm not anxious to tackle. There doesn't seem to be a lot of info about what dash panels can be removed to get to this actuator though? I did see one comment that they accessed it through the glove box hole but does that leave enough room to get a sawz-all in there? I do have an angle grinder that might be easier to use for cutting that bracket, so I guess I'm just wondering if you know of any threads with pics specifically targeting the passenger blend actuator? (And yes, I'm off to hit the search function as well)

 

[Mooseman]

I just found this one:

NEED HELP Thread 'Warm Air Only on Passenger Side'

May 5, 2020

No matter where I put the temperature control, the passenger side is always blowing warm air. The heat-vent-defrost control works fine. How do I replace the offending actuator?

• JimInRadfordVA
• Replies: 11
• Forum: Technical Discussion

 

[Shdwdrgn]

Damn that's a great pic, but seems to indicate that you can't just permanently bend the bracket out of the way since the glove box needs to mount to it again. And I guess getting an angle grinder into that position is also out of the question. Ah well at least now I can better plan for what I'm up against. Thanks!

I also found a long thread on the old TV site about this, and a few people found their actuators were simply "stuck". Turning it manually by hand and then performing a reset seemed to solve their problem so I'll try and give that method a shot as well before I get into the task of cutting that bracket.

 

[Shdwdrgn]

Well it took me forever to get back to this, but these hot temps have really been getting to me on the drive home. I picked up a cheap set of dremel burrs from Amazon awhile back, and that actually made quick work of cutting a large enough slot in the bracket to access the screw head. What *really* took a lot of time was then trying to find someone that had a 5.5mm deep-well socket that would reach in there. Finally found one at Ace and grabbed a 6" extension for my 1/4" socket as well.

So for the next person who has to do this... What I actually struggled with is the fact that the old actuator would ALMOST (but not quite) come off of the shaft before it hit the bracket. Trying to find something to move the bracket far enough was a challenge, but what finally did the trick was simply using a claw hammer resting up against the old actuator (because if I broke it, well it was already broken?). I managed to move the bracket about 1/8" inch, which still left it in line with the bolt hole at the bottom-left of the glove box frame (this was the only bolt around the glove box I needed to remove). It wasn't quite enough, but close enough that I could pull on the bracket with one hand and pull out the actuator with my other hand at that point. Then pop the new actuator in place, rotating it until it lined up with the flat spots on the shaft, pop the two screws back in, and presto!

I do wish I'd thought to pull fuses 36 and 39 ahead of time, and the smaller green one was a real bear to get out, but I let it sit for about 15 minutes, turned the key to run (without starting), and waited a minute... hmm not a whole lot of noise from resetting the actuator positions like I expected -- did I do something wrong? If I have to, I could just pull the battery cable again, but I did expect more to happen. It is certainly blowing cold air again as expected, so that seems promising, but I probably won't know for sure until I get it on the road and warmed up again.

 

[Mooseman]

To reset/relearn the actuators, you only have to pull the HVAC-B fuse for a minute, put it back in, then turn the key to RUN but don't start the engine. You should hear the whirring of the actuators. Don't touch any of the controls during this time. Only takes a couple of minutes.

You might need to put your ears closer to the HVAC system to hear them. They are usually pretty quiet. Without a good scan tool like a Tech 2 that can show HVAC system data, you can't definitively tell if the actuators are working exactly as commanded. If you don't hear them but the system still works as expected, I would call it good.

 

[TJBaker57]

What I actually struggled with is the fact that the old actuator would ALMOST (but not quite) come off of the shaft before it hit the bracket

I removed the actuator top cover first. This allowed me to remove the actuator without ever having to cut anything at all.

Naturally this only works if the replacement actuator is of the same sort of construction.

 

[Shdwdrgn]

To reset/relearn the actuators, you only have to pull the HVAC-B fuse for a minute, put it back in, then turn the key to RUN but don't start the engine. You should hear the whirring of the actuators. Don't touch any of the controls during this time. Only takes a couple of minutes.

You might need to put your ears closer to the HVAC system to hear them. They are usually pretty quiet. Without a good scan tool like a Tech 2 that can show HVAC system data, you can't definitively tell if the actuators are working exactly as commanded. If you don't hear them but the system still works as expected, I would call it good.

Huh and from what I read in previous threads, I fully expected to hear them "slamming" back and forth to learn their new positions. Well I might be running to grab some lumber after work today, that should warm up the truck enough to see what's blowing out.

 

[Shdwdrgn]

Wouldn't you know it... I went to pick up some lumber today and it was a full 40 degrees cooler than Wednesday, so the truck was giving me heat anyway. Ugh 49 today, back up to 81 again tomorrow, and back down to 49 again next Tuesday. Well I see Monday at least will be warm enough to see what temperature of air is blowing out the vents now.

 

[Mooseman]

At least you're getting some heat. It's supposed to be spring here, hasn't happened yet. Working on my TB later, hoping for -1c

 

[Shdwdrgn]

Unfortunately we've gotten nothing BUT heat, never had a Winter, so received almost no snow. The reservoirs are drying up and we're looking at one of the worst droughts ever. Denver has already gone on water restrictions so it's pretty bleak unless we start getting some serious rain.

Finally getting around to doing an oil change here today though as it warms up, just got in a new case of Amsoil this week. Hmm I should probably check on the transmission fluid too, I don't remember the last time that was changed.

[Edit] Ugh I will never understand how I can only drain 2 quarts (including what was in the filter), and the stupid idiot gauge was only just starting to bounce if I gunned it while the warning light still wasn't coming on (and yes, the light does work). Talk about planned obsolescence. And somehow after all these years I still haven't gotten around to putting in a real gauge.