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Any changes to your heating or AC layout (vents, other equipment) prior to this noise?
When did this noise first become evident to you? Just a shot in the dark, but it sounds like vibration in the...

I would agree with HVAC1000 that it really never hurts to breed your zones, but be careful not to introduce more air.

Just wondering, and this may or may not be pertinent, but has anyone bothered...

There is a lot of information missing that may be critical as to why your Heat pump may have quit again:

Good questions to ask:
-Is there an outdoor temperature sensor?
-What is the temperature...