Pretty Loud Click or ping on start of Air Handler, shuts of with one knock sound

by John
(Asheville, NC)

It's a new (6 weeks) Bryant heat pump and over the last week a click on startup appeared. Definately in the air handler. When the air handler shuts off there is a single knock sound, like knuckles on wood.

There was an installation problem. The temp was about 15 degrees outside that day. When initially installed the main wires in the air handler came loose from the wire cap that night, the air handler made a double popping sound and cut off. It popped the breakers, and set off the smoke alarm (I could smell the melted wires. They showed me where the main line in the AH had come loose and shorted.)

After the whole outdoor unit had been replaced, the air handler ran well for a month But the click started just a few days ago. Did an air handler component get fried? The contractor offered me a five year labor warranty in addition to parts (labor is normally one year)to cover anything that may have been damaged and may break down in the five year period. Should that be an acceptable remedy or do I have a compromised air handler?)

Or am I just overly worried about the noise. I really do believe it is a new symptom (or has it always clicked and I just didn't notice?)

Thanks
John