My 2005 Chevy Avalanche has developed an intermittent clicking noise from what sounds like it's coming from behind the HVAC controls. It sounds as if a blending door is trying to open and I think it might be a vacuum line off or loose. It doesn't do it at any certain time just randomly. A mechanic friend of mine seems to think it might be an actuator. Does anybody have any ideas as to what it might be ? I'm sure it's going to be a bear to access in the dash.
HVAC clicking noise in dash
- Thread starter gman2304
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It could be a servo for the vents.
that truck does not use any vacuum to move the doors. its all electric motors and gears.
Originally Posted By: Chris142
that truck does not use any vacuum to move the doors. its all electric motors and gears.
Yes, sounds like the gears are stripped in one of your actuators. I would suggest going to a forum for your vehicle and see what others have done to correct the problem. There are probably four or five of these things in there. Usually one has a higher failure rate. On my Cadillac, the shop manual showed disassembling the entire dash to get at the one that was bad. Other owners had figured out a short cut that was much easier.
that truck does not use any vacuum to move the doors. its all electric motors and gears.
Yes, sounds like the gears are stripped in one of your actuators. I would suggest going to a forum for your vehicle and see what others have done to correct the problem. There are probably four or five of these things in there. Usually one has a higher failure rate. On my Cadillac, the shop manual showed disassembling the entire dash to get at the one that was bad. Other owners had figured out a short cut that was much easier.
I have the same problem with my 05 cadillac. I would assume we have the same type blend door actuators. my car has 4 of them. two for driver/passenger temp and two for driver/passenger vent position. They wear out on the inside and will get 'stuck' and what you hear is them trying to move to the correct position. I can tell you that on my car you have to gut literally the entire interior to get to them. In the service manual the instructions literally start with "remove rear seats".... So I am living with it for now. Slike backwards under the dash while its making the noise and you will be able to see the motors struggling.
JHZR2
Staff member
My 318i has the compressor relay under the dash. I hear it click when the compressor cycles.
But if youre talking vacuum pots or something, definitely a chance. Do you see anything not working?
But if youre talking vacuum pots or something, definitely a chance. Do you see anything not working?
Thanks for all the replies. I have moved the settings to every position for both driver and passenger and they seem to change the air direction like they're supposed to....whether they're set for floor, dash, defrost or any combination in between. No rhyme or reason for when it does it. Sometimes when you start it up and the next time might be while I'm sitting at a stoplight 5 miles down the road. I'll check it out further in a few days...it's more irritating than anything else....having to explain to everybody that rides in it what that clicking sound is. LOL.
How loud/obnoxious is the clicking?
I have only encountered the blend door actuator problem in Impalas (many of them though), but it is LOUD. More of a loud knocking in the dash than just a click. It is rapid and aggressive. They will also not change vent direction.
The actuators in the trucks may be different or just so buried that they don't make as much noise.
My truck and the Colorados at work can make faint clicking noises when the blower fan ingests something. This is generally avoided on vehicles with cabin filters. I can't remember for sure, but I don't think an '05 Avalanche will have a cabin filter, so the blower may have sucked a pine needle or some other debris in.
I have only encountered the blend door actuator problem in Impalas (many of them though), but it is LOUD. More of a loud knocking in the dash than just a click. It is rapid and aggressive. They will also not change vent direction.
The actuators in the trucks may be different or just so buried that they don't make as much noise.
My truck and the Colorados at work can make faint clicking noises when the blower fan ingests something. This is generally avoided on vehicles with cabin filters. I can't remember for sure, but I don't think an '05 Avalanche will have a cabin filter, so the blower may have sucked a pine needle or some other debris in.
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It isn't a rapid sharp high pitch click and it does it with the ignition switch on but the fan turned off. I can move the blend knob to a different setting and hear the other actuators moving smoothly and quietly like they should. It seems to be one that is hung up and trying to move. It seems to be right behind the ash tray. No cabin filter on my Avalanche.
Nick1994
$100 site donor 2024
It's the mode door actuator. Just had it replaced on my grandmas Trailblazer. Once you get it out you can see the plastic gears in it and this one had a crack in it that didn't like to catch with the other gears. It clicked and eventually went to where you couldn't change the air direction. I'd get it done before it fails and your only air conditioning will be pointed at your feet lol.
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