In my other thread where I asked about running the Air Handler fan on Auto or on, I forgot to ask about the very loud Clunk the compressor contactor makes when it is De-energized. It is a little loud when it energizes too, but when it drops out: CLUNK!! I asked the installers and service tech about it and they said, yeah, every customer asks them the same thing.

I am in industrial automation, and have worked with high quality devices my entire career, but I've NEVER heard anything this loud either pulling in or dropping out.

What have the pros here experienced with this noise?

My condensor is Trane model 4TTR5049E1000BB, a 4 ton unit.