I am having a clicking sound coming from inside the dash. I assume it is one of the HVAC actuators going bad. I haven't been able to determine which one it is. Does anyone have any advice on pinpointing with one is going bad?
HVAC actuators
- Thread starter Machoman
- Start date
Just went through this exercise on a different vehicle (2003 Suburban) but the process will be the same. There are three actuators: Mode (controls where the air is directed, e.g. dash, floor, defrost, etc.), Blend (mixes hot & cold to adjust temperature) and Re-circulation (air from outside or inside only). Depending on the number of zones you may have more than one Blend actuator (the Suburban has two). Place all of the controls into their all-the-way On or Off positions. Turn the key on but do not start the engine. Listen for the clicking sound to start. As you listen to the clicking systematically adjust each control away from its initial position. Do this several times and listen for the clicking to stop and the restart once you get back to the initial all-the-way On/Off position. When you find the control (Mode, Blend, or Re-circulation) that stops the clicking you have found the offending actuator.
Mooseman
Moderator
Easiest to find which one is to put your hand on each one as you turn on the ignition and feel for it clicking. A diagram and part numbers of each one is located here:
gmtnation.com
a/c control issues 2005 TB
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...
gmtnation.com
Matt
Member
- Dec 2, 2011
- 4,022
Yep, easy. The only time you have to take apart the dash is to get one on the passengers side.
The three on the drivers side, remove the knee bolster and kick panel, the duct then get on your back in the footwell so you can see them.
It helps to have a goodly assortment of small sockets and short extensions as that one is a little tight in there. It is not either of the two near the plastic duct, it is the one closest to the center console.
Thanks for foto. Have a lot of tools, my wife’s car it’s an Jeep wk with Mercedes engine, this bastard is tight for everything you do.
Thanks again👍🏻
Thanks again👍🏻
Matt
Member
- Dec 2, 2011
- 4,022
The socket is 5.5mm. As @TJBaker57 mentioned which one it is, that's the hardest one of the 3 to get at.
Here is a followup to my earlier response (post #2). The mode actuator went from clicking intermittently to being silent & struck on Defrost. Ran a quick DTC check with the old ELM327 and sure enough it came back with B0263 - Air flow control #6 (A/C) circuit malfunction (note: in the screenshot below byte 3 - "98", is HVAC, and bytes 5 - "82" & 6 - "63" represent B0263).
On the assumption that the actuator needed to reset I pulled the HVAC fuse, waited 10 minutes, replaced the fuse and started up the truck. No joy, the actuator would not move out of Defrost.
As an interim fix (100degF plus in the garage right now!), I pulled the connector and manually rotated the actuator & cam assembly back into the Dash position (actuator hub turned all the way counterclockwise). Once the weather becomes a little more agreeable I will reconfirm the bad actuator and then replace it.
On the assumption that the actuator needed to reset I pulled the HVAC fuse, waited 10 minutes, replaced the fuse and started up the truck. No joy, the actuator would not move out of Defrost.
As an interim fix (100degF plus in the garage right now!), I pulled the connector and manually rotated the actuator & cam assembly back into the Dash position (actuator hub turned all the way counterclockwise). Once the weather becomes a little more agreeable I will reconfirm the bad actuator and then replace it.
I am going to attempt to feel the clicking with my hand after work. If I located the bad one, is it ok to drive to the auto parts store with the actuator removed?
I would think it would be OK. Might set a code but no worse than that.
If you are replacing either the mode or defrost actuator I would at least consider doing the two of them as a pair since they are likely both the same age and equally likely to fail at any moment. Plus they work together to direct airflow, and they are literally right next to each other so no additional work to speak of.
I want to share an absolutely brilliant & subtle piece of HVAC actuator root cause failure analysis. Per the description on Youtube, "In this video I have a look at an older GMC Sierra that had a customer complaint of the HVAC being stuck on defrost. My gut told me "prolly just a bad actuator." However, the data showed us something different".
ugg...I figured out the one that is ticking. I can't fell it ticking, but I can see the silver (retaining ring?) moving back and forth to the ticking sound. It is the top one directly above The gas pedal. I can't see the wire harness. Does anyone know the part number and maybe have a video of how to remove this one?
Mooseman
Moderator
Mooseman
Moderator
Here is a picture of my originals. This is a 2002 with RPO CJ2 automatic controls. All years and automatic vs manual controls are NOT the same. So check YOUR model year and auto or manual controls before you buy.
And at a guess, this is what lilely happened. The plastic gear that drives the shaft has cracked and is rotating without driving anything.
