Front Defroster Suddenly Ticks

[l008com]

My Christmas present this year is a broken defroster. When I try to put my front windsheild on defrost, it just started doing this:

What do you make of that?
If I had to guess, I would say a broken fan box and the fix is to fully take the whole dash apart to replace some $3 part?

Please oh PLEASE tell me I'm wrong!

I don't think it ever stops or ever start blowing the bulk of the air out the front defroster. I don't use the front defroster very often, I generally keep the HVAC on auto or on vent & floor combo. Only when theres actually nice on the front window, do I switch it over.

 

[movietvet]

Depending on if you have manual controls or automatic controls, I did not watch the video, you can go to you tube and watch at least 3 videos, of each kind, for doing a reset on the heating-a/c system. I say 3 of each because there are some flakes out there that do not know how to communicate to other people. A friend of mine, had a manual control system and had some clicking noises and I did a reset and has worked fine for 8 months now.

I just listened to the noises. That is louooodah! Metal on metal. Try the reset and see what happens.

 

[l008com]

I don't think its quite as loud in person as it sounds in the video. The phone was closer to the dash when I recorded the audio, than the camera was when i took those random pictures.
In person it does not sound like a metal on metal sound, it definitely sounds like plastic. But still pretty hard for a plastic bang

 

[Mooseman]

Yep, try the reset but I'm putting money on the actuator being DOA. Classic symptom.

Post in thread 'a/c control issues 2005 TB'

Sep 11, 2012

Welcome! This is the new clubhouse for discussing technical issues. Curious how you discovered us, since trailvoy attempts to censor any mention of the couple thousand "disloyal ones".

Anyway, it really takes a GM Tech II tool to take control of the HVAC control module and put each actuator through its paces. If you recently changed or discharged the battery, the lack of voltage to the control module memory forces each actuator through a recalibration process. That process is often stressful to older actuators and they get flaky or die.

Perhaps you've seen my main actuator...

• The_Roadie

 

[movietvet]

Yep, try the reset but I'm putting money on the actuator being DOA. Classic symptom.

Post in thread 'a/c control issues 2005 TB'

Sep 11, 2012

Welcome! This is the new clubhouse for discussing technical issues. Curious how you discovered us, since trailvoy attempts to censor any mention of the couple thousand "disloyal ones".

Anyway, it really takes a GM Tech II tool to take control of the HVAC control module and put each actuator through its paces. If you recently changed or discharged the battery, the lack of voltage to the control module memory forces each actuator through a recalibration process. That process is often stressful to older actuators and they get flaky or die.

Perhaps you've seen my main actuator...

• The_Roadie

Yep. First thought is always the actuator but I was surprised when the reset took care of my friend's 2005 Tahoe with manual controls.

 

[l008com]

So I've been ignoring this all winter but time to revisit and fix.

Here's what I learned. Its actually clicking any time I try to take it OUT of dash-vent mode. Floor and vent is fine, vent only is fine. Any setting with no vent, clicks non stop. INCLUDING shutting the system off entirely!

I did not try any fuse pulling. It was a super cold winter so like I said, I just ignored it. Is it still worth trying that or do the symptoms indicate a definite hardware problem?

I'll probably have time to try the reset process Friday. If it is a hardware problem, what would it be exactly? And how hard is it going to be to fix it?

 

[Mooseman]

Definitely an actuator, likely the floor/dash vent one. If it's clicking, a reset is not likely to fix it but you can try. If it does, it won't be permanent.

 

[l008com]

Ok update time. I FINALLY got around to doing the reset. There were 4 HVAC fuses and I yanked them all, checked my tire pressure all around, then put them back in.

Unfortunately, things are much worse now

It now clicks for a minute or two straight, every single time I turn on the truck.

So, actuator it is? How many actuators are there? What is ACTUALLY happening/failing here? Is this something I can fix by removing the center console but NOT removing the whole dash, hopefully?

 

[Mooseman]

There are 5 actuators:

Post in thread 'a/c control issues 2005 TB'

Sep 11, 2012

Welcome! This is the new clubhouse for discussing technical issues. Curious how you discovered us, since trailvoy attempts to censor any mention of the couple thousand "disloyal ones".

Anyway, it really takes a GM Tech II tool to take control of the HVAC control module and put each actuator through its paces. If you recently changed or discharged the battery, the lack of voltage to the control module memory forces each actuator through a recalibration process. That process is often stressful to older actuators and they get flaky or die.

Perhaps you've seen my main actuator...

• The_Roadie

Try each control individually. For the mode, go from defrost to dash vents for the defrost actuator, then from dash to floor for the floor/dash actuator, then each side temp for those two. Then try the recirc. Hopefully that one is fine as it does require dash removal. Pass side temp actuator requires some cutting of a dash brace located right in front of it.

 

[TJBaker57]

Ok update time. I FINALLY got around to doing the reset. There were 4 HVAC fuses and I yanked them all, checked my tire pressure all around, then put them back in.

Unfortunately, things are much worse now

It now clicks for a minute or two straight, every single time I turn on the truck.

So, actuator it is? How many actuators are there? What is ACTUALLY happening/failing here? Is this something I can fix by removing the center console but NOT removing the whole dash, hopefully?

Personally, I would begin by replacing BOTH the MODE and the DEFROST actuators. These are the two that control where the airflow goes AND they are the easiest to do. They are right next to each other on the drivers side above the area of the accelerator pedal. On my 2002 after the lower dash/footwell covers are dropped there is one plastic air duct that needs to come out to get good access to them.

 

[l008com]

It occurs to me that if these are THAT easy to get to, I can probably just put my hand on them while i turn on the truck and feel which, if any of them, are the ones ticking. Hopefully I have time for this soon because its incredibly annoying.

 

[movietvet]

It occurs to me that if these are THAT easy to get to, I can probably just put my hand on them while i turn on the truck and feel which, if any of them, are the ones ticking. Hopefully I have time for this soon because its incredibly annoying.

If you have a mechanics stethoscope, use it. If not, get one. I use mine all the time.

 

[l008com]

So switching between floor and vent doesn't work. The defrost comes on and off when its supposed to. I'm going to turn recirc on and off right now but based on EVERYTHING, seems like the floor/vent one is the problem. Which I guess I could have also inferred from the initial symptoms too. Runs fine on floor. Clicks any time you try to change it off floor including shutting the system off.

So the other post has a diagram of the actuators:

The thing that makes me nervous still is that while the malfunction strongly points to the floor/dash actuator, if i move my head around my dash while its clicking, it really sounds like its coming from the area where the recirculate actuator is. But this is also the first broken actuator I've ever listened to, so I don't really know how its supposed to sound when each different one is broken.

Also, regarding the diagram, they list the part number for "Airflow Mode Actuator", but the diagram shows a "Floor/Dash Vent Mode Actuator", are those the same part? So if that is the one thats broken, those are the part numbers?

Also at this point, is the easiest way to confirm 100%, just go get under there and unplug the dash floor actuator, then turn on the truck and see if it still clicks?

 

[l008com]

Jesus the ads on this site are getting out of hand. In both grossness and quantity that can even grind a fast computer to a halt.

ANYWAY, ok so heres the deal. Never air out of vent, always air out of floor. Changing between the two does nothing. Which sure sounds like the floor/vent actuator.

BUT

Also when I hit recirc, it, flashes for a few seconds and then goes out.

Which suggests both, but the odds of both failing are once are low enough that I doubt I have two that are bad.

 

[movietvet]

Jesus the ads on this site are getting out of hand. In both grossness and quantity that can even grind a fast computer to a halt.

ANYWAY, ok so heres the deal. Never air out of vent, always air out of floor. Changing between the two does nothing. Which sure sounds like the floor/vent actuator.

BUT

Also when I hit recirc, it, flashes for a few seconds and then goes out.

Which suggests both, but the odds of both failing are once are low enough that I doubt I have two that are bad.

Do the one and will likely be fixed.

 

[TJBaker57]

Also when I hit recirc, it, flashes for a few seconds and then goes out.

Are you aware of what the recirc actually does??

The sole action of the recirc is to allow air from outside the vehicle to be drawn in or not. It has absolutely zippety-do-dah to do with where the air blows out.

 

[movietvet]

Are you aware of what the recirc actually does??

The sole action of the recirc is to allow air from outside the vehicle to be drawn in or not. It has absolutely zippety-do-dah to do with where the air blows out.

Exactly why, with recirc on, the a/c blows colder. Is reusing the same interior air.

 

[l008com]

Are you aware of what the recirc actually does??

The sole action of the recirc is to allow air from outside the vehicle to be drawn in or not. It has absolutely zippety-do-dah to do with where the air blows out.

Yeah, the recirc has nothing to do with the vent, yet they both seem to be broken, which is the dilema.

 

[Mooseman]

If the recirc actuator is broken, you're in for a world of pain.

M

Thread '2003 Trailblazer Vent \ Recirculate Actuator'

Oct 23, 2023

Hello all.

Thank you in advance for anytime you can spend assisting me. My wife has a 2003 Trailblazer with manual HVAC system. I have to replace the Recirculate \ Vent actuator because it is not shutting off at the limits and now is making a whining noise. I was able to find out from researching on this forum that I do have to take the dash pad off to replace it but what I need to know now is the part number before I start the teardown. I will be using my brother shop for the repair and I cannot tie up a bay because of a wrong part. I keep seeing 604-126 and 604-106. To me it...

• mrwhipper
• Replies: 8
• Forum: Technical Discussion

• 

I would replace the mode (floor/vent) actuator first, reset/relearn it, then see if the recirc is also busted.

 

[TJBaker57]

My recirc has been broken for more than 10 years. I don't consider it worth repairing.

However, I live in a very dry climate and get as low 32° F out of my A/C system.

 

[dhanger]

If the recirc actuator is broken, you're in for a world of pain.

I recently had to repair the recirc actuator (I didn't replace it, I repaired it by taking it apart and installing roll pins, documented elsewhere here). Here in Arizona it's almost a requirement to have it working. Even after reading up on the procedure and having head knowledge, it was still a major ordeal. It took me nearly 2 days to remove and replace the dash, and I'm retired with little to do most the time. My only advantage is that I'm a small guy and pretty wiry, although at 68 years not so much any more. If one can live without the recirc it's my advice to leave it, unless you're just bored out of your skull, which you will be (out of your skull) afterwards.

 

[l008com]

I can definitely live without recirc, UNLESS thats the actuator doing the clicking. Unfortunately I am not bored and have very little free time

 

[l008com]

Personally, I would begin by replacing BOTH the MODE and the DEFROST actuators. These are the two that control where the airflow goes AND they are the easiest to do. They are right next to each other on the drivers side above the area of the accelerator pedal. On my 2002 after the lower dash/footwell covers are dropped there is one plastic air duct that needs to come out to get good access to them.

View attachment 119552

Ok how did you get this kind of access? I took all of my under-dash plastics off and I can't see anything? Its like I have no access at all, even these easy two actuators seem buried up in there. I'm heading to youtube now but if you have any tips let me know.

 

[l008com]

Update!

I pulled half of my dash apart, including removing the radio. And I was able to determine which actuator is clicking....

Maybe.
I Mean I got hands on the clicking actuator, and I unplugged it and started up to confirm that it IS the problem actuator.



But looking at the diagram, I'm still not sure which one I was touching.
I'm not sure if it was the floor/dash, the drefrost or the driver's temp.
Is my only option at this point to yank it and read its part number?

I'm not going to do that now, I'm just going to leave everything as is and hopefully tackle this next week.

Also, is the "Floor/Dash" actuator with the red arrow, the same as the "Airflow Mode Actuator" in blue? I assume thats the same part but they really should have labeled them the same. And when I look up the part number on NAPA, it has yet another name lol.

So I guess my question is, is there an easy way to definitively confirm which one it is? I had to lay on my back and reach up through the bundles of wire to even get it so I'm not sure I can even take a decent picture of it, but I'll try.

 

[movietvet]

"I Mean I got hands on the clicking actuator, and I unplugged it and started up to confirm that it IS the problem actuator."

How do you know it was the clicking actuator, if you unplugged it BEFORE you started up? It would not be clicking if the key/engine is not on/started. You unplugged first and then started. If it always clicked and you unplugged it and then started and there was no clicking, the correct actuator is the UNPLUGGED one.

What I am trying to say is.....if you unplugged it and you can see in the pic the locations, you should be able to feel to find the correct actuator.

I learned a long time ago, that as a tech, I have eyes in my finger tips.

 

[l008com]

In addition to putting my hands on it while it was clicking, confirming it was definitely the one doing the clicking, I unplugged it with the truck off, then started it up, and no click. It is currently clicking for a minute or so solid, every single time I start up the truck. Except now since unplugging it.

Here's the best photo I could get, which turns out might be good enough!



I zoomed and distorted the photo until I was able to make out the part number. It doesn't match any of the numbers on the previously-linked to actuator part number diagram.

That number (52411434) does not come up on a rockauto search or a napa search. But when I GOOGLE it, I get a ton of actuator matches.

Although they all call the part something different so I guess I'm still not 100% sure which actuator this is Can anyone confirm with certainty that this is the "Floor/Dash Vent Mode Actuator" ?

 

[movietvet]

You have an "X" on one and a circle on the other. I can only assume that the circled one is the one you are talking about, correct? But it does look like it is unplugged and the connector is turned sideways.

By the way, did you say what the year and model of vehicle this is? Did you and I missed it?