I knew I bragged too much on my Z71

[OR VietVet]

Everything has been going along great with my 2005 Z71 since I was involved in my Build Thread. 5500 mile round trip last July with absolutely no problems and since back in the PNW, I have had nada for problems.

I really don't have a problem yet but today my girl, Linda, heard a very slight tapping noise coming from the area around the glove box. She said, "like someone is knocking at the door". I had to really concentrate but then I agreed with her, the noise was there. We had the a/c on because her hair is curly and she gives me holy hell for what the windows down wind does to her mane. I have not turned off the a/c while driving to see what happens with the noise but I suspect her sensitive hearing picked up an actuator noise. The a/c works flawlessly and is ice cold and comes out of all the right holes at the right times and the blower is top notch.

Does anyone have a different opinion of what the noise may be? It is not a blower motor bearing or cage noise, I know what that sounds like and the motor assembly and harness were all replaced recently. The blower speed does not change the noise at all, speed or volume.

My plan is to now remove the glove box and get my mechanic's stethoscope out and find the noise source. I also have a nagging feeling I have another electrical problem at the rear junction block inside the frame area. May not be the junction block but will go in to details in another thread, in the correct section.

 

[bill1013]

Sounds like you’ve got the right idea. Just take it slowly and methodically and you’ll get it. Good luck and let us know what you find. Aloha!

 

[swathdiver]

Behind the glovebox is the recirculate door above the fan motor. It could be that the foam on the door has worn away and the actuator is trying to compensate for it being missing. In another car, the air was not so cold but thought I would throw that out there.

 

[ivin74]

ILinda, heard a very slight tapping noise coming from the area around the glove box.

Have you changed out any of the AC actuators? I had a similar sound on my suv, I changed out the top AC actuator and the noise disappeared. Food for thought, might not be your case but something to think about.

 

[S33k3r]

Is it possible there is debris in there?

 

[Doubeleive]

Is it possible there is debris in there?

sometimes the actuators get funky, there is a metal contact inside and I think a resistor so it knows where to move the door depending on the command full open/middle/closed
I think the contact gets poor over time and then it doesn't know where to go exactly so it moves back-n-forth making a clicking noise.
sometimes they do it no matter where you set the temp or direction and sometimes if you back it off a hair from say full cold or full hot then it may be ok there and stop clicking

 

[Fless]

Could use a Tech 2 to monitor the actuator positions (commanded and actual) to see if one is wandering around to find the commanded spot.

 

[OR VietVet]

Thanks all for the comments. To answer a question from @ivin74, no I have not changed an actuators or any other a/c components. The only part that has been changed is the blower motor and the harness.

 

[iamdub]

Thanks all for the comments. To answer a question from @ivin74, no I have not changed an actuators or any other a/c components. The only part that has been changed is the blower motor and the harness.

There you have it. A system that you haven't totally rebuilt is one giving you issues. It does sound like an actuator that can't find its intended position, like from a split gear or dirty contacts. Weren't you gearing up for an A/C overhaul, or at least the diverter plenum?

 

[OR VietVet]

There you have it. A system that you haven't totally rebuilt is one giving you issues. It does sound like an actuator that can't find its intended position, like from a split gear or dirty contacts. Weren't you gearing up for an A/C overhaul, or at least the diverter plenum?

You are correct. I have already looked up all the needed parts and have plans to do the major a/c overhaul, when and if the system has a problem. I am going to do my inspection process tomorrow. My girl has given me strict orders to get the grass cut, front and back yards, while the temps are low. I sitting at 57 degrees right now. Also have to do my dry rub on some sirloin and tri tip steaks for grilling later today for our surf and turf dinner plans here. I think my a/c noise inspection will be tomorrow and my trailer light concerns as well, since she will be here to run the lights while I am under the back of rig. I have another thread started about that concern.

 

[iamdub]

You are correct. I have already looked up all the needed parts and have plans to do the major a/c overhaul, when and if the system has a problem. I am going to do my inspection process tomorrow. My girl has given me strict orders to get the grass cut, front and back yards, while the temps are low. I sitting at 57 degrees right now. Also have to do my dry rub on some sirloin and tri tip steaks for grilling later today for our surf and turf dinner plans here. I think my a/c noise inspection will be tomorrow and my trailer light concerns as well, since she will be here to run the lights while I am under the back of rig. I have another thread started about that concern.

I don't recall if it was with the '800 or '900, but there's an actuator on top of the plenum (maybe the one in question?) that, with a few easy tricks, is replaceable without all the hassle outlined in the shop manual. I'm pretty sure I recall someone posting pics and describing how to do it. It might be something as minor as low headroom and a 7mm (or is it 8mm? I always use a 9/32") nut driver bit in a 1/4" box end ratchet is the trick.

One of these:

In something like this:

It makes for a really low-profile nut driver. I use such a setup at work for one specific task. I have a zip tie on the shank of the bit that extends through the ratchet wrench. I had planned on drilling the bit to press a roll pin through to lose the zip tie and make it even more low-profile. But I like being able to easily remove the bit as needed.

 

[Doubeleive]

I don't recall if it was with the '800 or '900, but there's an actuator on top of the plenum (maybe the one in question?) that, with a few easy tricks, is replaceable without all the hassle outlined in the shop manual. I'm pretty sure I recall someone posting pics and describing how to do it. It might be something as minor as low headroom and a 7mm (or is it 8mm? I always use a 9/32") nut driver bit in a 1/4" box end ratchet is the trick.

One of these:

View attachment 400436


In something like this:

View attachment 400437


It makes for a really low-profile nut driver. I use such a setup at work for one specific task. I have a zip tie on the shank of the bit that extends through the ratchet wrench. I had planned on drilling the bit to press a roll pin through to lose the zip tie and make it even more low-profile. But I like being able to easily remove the bit as needed.

the actuator bolts should all be 7mm, a couple are 5.5mm

 

[OR VietVet]

I have all those sizes and tools in my collection. I have been buying older SK and MAC 3/8" and 1/2" drive ratchets that I used to use when wrenching in the shops. They don't make them any more and I remember that they felt great while using.

 

[ivin74]

I am going to do my inspection process tomorrow.

Keep us posted on your findings

 

[iamdub]

the actuator bolts should all be 7mm, a couple are 5.5mm

Thanks. I can never remember. I just know the 9/32" socket works on the 7mm. It's a little loose, but them screws don't require a lot of torque. Now that I have factual numbers, I should add these specific sizes to my Tahoe-specific toolbox.

 

[OR VietVet]

Just to let you know, I did try to diagnose this yesterday but there was no noise at several different settings.

 

[iamdub]

Just to let you know, I did try to diagnose this yesterday but there was no noise at several different settings.

These actuators tend to start out failing intermittently before they completely fail. Yours might've wiped the electrical contacts clean with all of its cycling. Or the gear clicked back to its home position again. For now.

 

[OR VietVet]

These actuators tend to start out failing intermittently before they completely fail. Yours might've wiped the electrical contacts clean with all of its cycling. Or the gear clicked back to its home position again. For now.

Let's hope so.

 

[ivin74]

Just to let you know, I did try to diagnose this yesterday but there was no noise at several different settings.

Mine did the same thing, some days you could hear it clicking and other times I would not hear it for days or even weeks, the issue was very random.

The best time to diagnose it is when you hear the noise. I know that would not be the ideal time but that would rule out buying the actuator and not being the root cause of the problem.

I bit the bullet, bought it, installed it and have not heard any noises since. That was 2 years ago. I've taken several 8hr road trips and no issues yet.

 

[OR VietVet]

Mine did the same thing, some days you could hear it clicking and other times I would not hear it for days or even weeks, the issue was very random.

The best time to diagnose it is when you hear the noise. I know that would not be the ideal time but that would rule out buying the actuator and not being the root cause of the problem.

I bit the bullet, bought it, installed it and have not heard any noises since. That was 2 years ago. I've taken several 8hr road trips and no issues yet.

Questions: Was the noise you heard coming from right behind the glove box? Which actuator did you replace to fix that noise? Time it took to replace? Was it easy access or PITA access? Thanks.