Help finding an answer with A/C issue

[LT1ZOB]

I’m almost positive I’ve seen it on this forum, but can’t find the thread I’m looking for. Once in a while, when I come to a stop, i here my AC buzzing. Not annoying, loud buzzing, just sounds louder than it should be. As soon as I shut off the AC, the noise stops. It happens very seldom, most of the time all is quiet and normal.
I remember reading something about this here, but then again, I’m on 3 different GM forums and sometimes get my info mixed up. Anyone know what I’m talking about? I remember it being a fairly simple solution like rewrapping the AC line entering the firewall??? Please help if you can.

 

[LT1ZOB]

Bump. Trying one more time

 

[BG1988]

I’m almost positive I’ve seen it on this forum, but can’t find the thread I’m looking for. Once in a while, when I come to a stop, i here my AC buzzing. Not annoying, loud buzzing, just sounds louder than it should be. As soon as I shut off the AC, the noise stops. It happens very seldom, most of the time all is quiet and normal.
I remember reading something about this here, but then again, I’m on 3 different GM forums and sometimes get my info mixed up. Anyone know what I’m talking about? I remember it being a fairly simple solution like rewrapping the AC line entering the firewall??? Please help if you can.

second fan

 

[LT1ZOB]

second fan

Sorry, not following your comment. Can you be a bit more specific? Thank you

 

[BG1988]

the second radiator fan.. on HIGH MODE


other wise it's perfectly normal..

 

[Big Mama]

Is it a new problem?

 

[Rocket Man]

Unplug the fans next time it happens and see if it goes away.

 

[LT1ZOB]

Thanks guys. So are you saying it’s normal? The second I shut the AC off it goes away, never unplugged the radiator fans

 

[Rocket Man]

Thanks guys. So are you saying it’s normal? The second I shut the AC off it goes away, never unplugged the radiator fans

Have you opened the hood to try and listen where the noise is coming from? It could be the compressor or clutch too.

 

[LT1ZOB]

Have you opened the hood to try and listen where the noise is coming from? It could be the compressor or clutch too.

I have not. I’m familiar with compressor noise, I wouldn’t say it’s the compressor. It happens seldom, it’s almost like a noise frequency

 

[Big Mama]

I’m with BG if you’ve always heard it. My 2nd fan is louder too but if the noise is new it should be monitored or repaired before it becomes a bigger issue. After you drive it one day leave it running and get out. If you hear the sound open the hood and try to locate it. If it’s the 2nd fan it should come on for a bit then turn off.

 

[LT1ZOB]

I’m with BG if you’ve always heard it. My 2nd fan is louder too but if the noise is new it should be monitored or repaired before it becomes a bigger issue. After you drive it one day leave it running and get out. If you hear the sound open the hood and try to locate it. If it’s the 2nd fan it should come on for a bit then turn off.

Ok, so very hot today, had the air on all day and happened to hear it again. Pulled over, opened the hood, all is normal sounding. Both fans were on. Can’t hear the sound from the outside or under the hood. It’s almost like the sound of bass coming from the car next to you, but only inside the car. Under the hood, all is good and sounds normal

 

[Rocket Man]

Noise cancelling in the stereo? The 15+ have so many weird noise issues from buffeting to noise cancellation. Sorry I’m not much help. A sound clip might help, it’s really hard to diagnose noises especially if we don’t get to hear the noise. That’s a lot of uses of the word noise.

 

[LT1ZOB]

Thank you guys. I’m starting to think I’m being hyper sensitive. I think it’s just normal with the AC on, 92degrees outside and the car has been running all day. If I can catch it, I’ll make a clip

 

[juniorwatson]

You need to be a HELLUVA lot more descriptive with anything.

Do you hear the noise in the cabin? If so, does it get more noticable when you are at a stop with the engine running, and the blower motor off?
Is it more noticable outside the cabin? It it more noticable under the hood? Are there any changes when the A/C clutch kicks in and out? Is there any change, if applicable, when the mechanical fan clutch engages and disengages?
-Does the noise start when the engine is running? Is it noticable as yu are driving, or only at stops? Does it change with drive speed, or transmission gear?

You see where I'm going? There's a $hit ton of things it could be, but we haven't got a clue as to where to start since you didn't provide any useful data to start.

-Junior

 

[91RS]

What year is your truck? If it’s a 17, there’s a bracket for the AC pipe to fix a buzzing at idle.

 

[petethepug]

Sent from my iPhone using Tapatalk

 

[LT1ZOB]

Thanks guys. My Tahoe is a late 16 production, right before the shutdown to switch to 17 m.y. It is not the speaker for sure. The noise, when it happens, is only audible inside the vehicle, not under the hood and not outside the car. If you’ve had a high hp car with exhaust that sometimes drones, it’s almost a droning sound.
91RS, your bracket comment is exactly what I was remembering when I posted this thread. Can you elaborate? Any threads here on that bracket?

 

[91RS]

I’d have to look up the bulletin again to be sure but I’m pretty sure it only applies to 17s with 1234yf.

 

[LT1ZOB]

I’d have to look up the bulletin again to be sure but I’m pretty sure it only applies to 17s with 1234yf.

Thank you. Please let me know what it says if you find it. I did put a 13mil deep socket on the bracket. Got 1/2 a turn out of it. (Obviously not much force applied.