GMC Sierra strange noise from Air Conditioning

Harold Rutherford · February 24, 2018

I have a 2016 Sierra SLT Z71 the Air conditioning started making noise after about a year, had it in service 4 times they changes fan, compressor and cabin filter clean system no help. The noise stops when A/C is turned off and the fan still running and starts again when A/C is turned back on gets louder as engine revves. Anyone have an idea what the problem can be? Service can't find a fix and I'm going crazy. The 4 loaner trucks I have been driving while being serviced are very quite. This is my 8th new GMC Sierra first time had a problem.

HoosierZ · February 24, 2018

How would you describe the sound?

My 2005 Colorado had a whistling sound from the firewall area that turned out to be from an AC line under the hood running along the top of the firewall. It was a design flaw that was replaced with a redesigned line that was relocated along the fender. The noise went away.

Harold Rutherford · March 3, 2018

It only starts after A/C runs about 30 seconds, it sounds like a light knocking sound with a light chirping sound it gets faster as engine revs It stops completely when A/C is turned off, the heat is quite so its not the fan (they replaced the fan and A/C compressor under warranty but did not stop noise.) The noise started about 3 months ago was very quite for the first year. I have to give the dealer credit for trying but this is the 4th trip in for the same problem and no one seems to know what it is. The loaner trucks I have been driving are quite no A/C noise.

seamus2154 · March 3, 2018

I am having the same exact issue! The new compressor was a slight improvement but the sound is only there when the compressor is on, It is whirling and is like chinese water torture for me in town. At highway speeds other noise drowns it out. But in town at slow speed especially if the radio is not loud, it will drive you to drink!! 4th truck in this platform, problems with all of them, I have about had it with GM's poor design of basic things. This truck is so improved over the others and I am hating it because of this and the lousy uncomfortable seats in a luxury truck!

silveradosid · March 3, 2018

have they checked the belt tensioner for a broken spring it can still have tension with a broken spring but it will rattle

seamus2154 · March 3, 2018

Doesnt make a sound under the hood all sounds normal till you are in the truck and the ac kicks on. 8ooo miles. ridiculous

Mikesuell4 · May 16, 2023

Did you ever find a fix for this? I have the exact same problem. Mine started after i had a new ac compressor installed. A year later I had another 1 installed with a new belt and it has gotten even louder.

DB2017 · June 17

Hello, I also had a random noise coming from the A/C unit (after changing the cabin air filter) It is best described as a low tone rumbling sound. I pulled the A/C motor out and sure enough, a nut (from a tree) had slipped down into the fan. It was tumbling around when the fan was running. Now looking at it, it is the exact sound you would hear if a tree nut shell was tumbling around a plastic fan. Anyway, an hour later she is back together and working great. Saved my self a large amount of money so...thank you everyone.

Edited June 17 by DB2017
To add a picture