Hi,
I have a 3 yr old Trane XL15 that started making noise about a week ago. At first it wasn't too bad but it got louder and more frequent. Three days ago it was almost constant whenever the a/c came on. This time of year in the south, it comes on a lot. I was lucky as the service guy came out within an hour. Of course the a/c did not make any noise while he was here checking things out. Trying to explain an a/c noise is like trying to explain a car noise to your mechanic. Anyway, the best I could come up with was, it sounds something like the icemaker coil when it gets too close to the back of the fridge and the wall, only louder.

He checked out everything and replaced what he called a heat sequencer that he thought was bad. It seemed ok at first but yesterday I noticed a few times a slight noise, today it's more frequent but not all the time, however; it is still annoying.

I tried to record the noise before calling service again but all I get is the fan noise.
Does anyone have any idea of what is causing this noise?

 

Outside unit or inside unit ?

 

Sorry, inside unit. It has been sporadic the past two days.

 

Needs to find out if it is the blower fan making noise first. SO, turn your T-stat to 'Fan only' and check to see if it makes noise. IF it does, then it is the fan, if not, it shoud be something else. but check the fan first, because fan is the only moving part in there.