First time poster so go easy.
I have a 9 year old Trane Heat Pump 12 (I don't know the numbers that follow might be XL or XB) and it's been working perfectly (both in cooling and heating mode). However, on Sunday night on startup and shutdown it has been making a clunk sound a second after the fan on the heat pump starts spinning.
It was unseasonably warm so the heat pump probably didn't run all day yesterday so I turned it on and no noise. It ran perfectly fine for a couple days without a noise and then last night (Tuesday) it made the noise again. I'm afraid if I call a tech out then he won't be able to replicate the problem and then I will still not have an answer. The unit is heating and cooling as normal.
Do you have any idea on what could be causing the clunk on the start cycle and then when it shuts off? It doesn't do it immediately when the fan starts.