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View Full Version : Carrier Unit Making clanking noise when shutting off


andyjan
Jul 15, 2008, 07:25 AM
Had a new Carrier Model 58STA/STX installed in December. While doing yard work we heard a loud clanking noise when AC unit shut off. Installer said this was normal. Anyone having same problem and is it normal?

hvac1000
Jul 15, 2008, 10:08 AM
I would not say it was normal but I am not there to hear it.

C A
Jul 6, 2012, 12:04 PM
Same problem here... called tech... said it was a valve inside the unit making the noise and it was normal. I always thought where there is mechanical noise there is wear but maybe not. Our unit is just outside the bedroom window so we sleep with headphones! If I could do it over again, I'd buy another brand...

hvac1000
Jul 6, 2012, 01:59 PM
It could be the fan motor outside has too much end play, or is mounted to low on the shaft or the fan blade hub is getting loose. All of these can cause a noise. I had one a while back that when runnit would soundOK but when it shut off it would clank. It was hitting inside the unit because when power was removed from the motor it allowed the motor shaft to drop down just enough to hit the inside of the A/C unit. In this case it was the top of the compressor ever so lightly but made that noise. The shaft on the motor should just have a slight up and down movement when the power is off. Sometimes you can raise the fan blade a bit to compensate but is it is a lot of movement from the motor then a motor replacement is in order. Give it a try.

C A
Jul 6, 2012, 02:43 PM
Now that all makes sense! I just can't believe the unit is built to be this noisy. Since I'm not mechanically gifted, will try another tech and ask him about these possibilities... THANKS!

hvac1000
Jul 6, 2012, 02:48 PM
No problem. Post back with the results please.