I have a recently installed York TM9X100C20MP11. It replaced a 20 yr old Carrier system.
When starting up I hear a low whine (like a turbine) until its get up to speed. The installer told me its normal for units with an ECM motor to whine.
When stopping the whine returns but for a longer time and is louder.
Towards the end (last few seconds) I hear a rumbling sound.
Are these sounds normal?
Thanks for your response.