Front Defroster Suddenly Ticks

l008com

l008com

Member
Joined
Feb 19, 2016
Posts
1,010
Location
Massachusetts
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.
 
  • Like
Reactions: 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.
 
Last edited:
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
 
  • Wow
Reactions: movietvet
Yep, try the reset but I'm putting money on the actuator being DOA. Classic symptom.

The_Roadie

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

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". :wink:

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...
 
  • Like
Reactions: movietvet
Mooseman said:
Yep, try the reset but I'm putting money on the actuator being DOA. Classic symptom.

The_Roadie

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

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". :wink:

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...
Click to expand...
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.
 
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?
 
  • Like
Reactions: movietvet
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.
 
  • Like
Reactions: movietvet
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 :Banghead:

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?
 
  • Wow
Reactions: movietvet
There are 5 actuators:

The_Roadie

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

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". :wink:

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...

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.
 
  • Like
Reactions: movietvet
l008com said:
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 :Banghead:

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?
Click to expand...


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.

IMG_20190318_143516.jpg
 
  • Like
Reactions: Mooseman and movietvet
l008com said:
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.
Click to expand...
If you have a mechanics stethoscope, use it. If not, get one. I use mine all the time.
 
  • Like
Reactions: Mooseman
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:
allactuators-orig.jpg
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?
 
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.
 
  • Like
Reactions: movietvet
l008com said:
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.
Click to expand...
Do the one and will likely be fixed.
 
l008com said:
Also when I hit recirc, it, flashes for a few seconds and then goes out.
Click to expand...


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.
 
  • Like
Reactions: movietvet
TJBaker57 said:
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.
Click to expand...
Exactly why, with recirc on, the a/c blows colder. Is reusing the same interior air.
 
You must log in or register to reply here.

Forum Statistics

Threads
24,275
Posts
648,662
Members
20,740
Latest member
benjamin.major13

Members Online

No members online now.
Total: 3,459 (members: 0, guests: 3,459)

Share This Page

Share This Page
Top Bottom
Back