I hope someone out there can help. I just bought a house and was told that the Gibson unit in it was a "contractor" model (low end). I read on this site where Gibsons seem to be noisy, which this one fits in perfectly. There is a very annoying buzz that seems to drone in the same rythm as the compressor outside. There is no hum when it is on fan only or emergency heat, only in heat pump mode. The unit is probably 3 years old. I guess it is a harmonic from the piping. I have plans to put rubber mats under the outside unit to see if this helps some, but here is possibly a clue: It warmed up the other day and I was able for the first time to put in A/C mode and there was no buzzing at all, plus the unit cooled well. So why would it buzz on heat pump and not on air conditioning?
Air handler is a Gibson Mod# GB38M-042K-B-1B, ser# GBD050207582.
Exterior Unit is a Nordyne Mod JT3BA-042KA, ser# JTD050361853.
Anybody have experience with this sort of problem so I can tell my a/c guy? Evidently there aren't too many Gibsons in this neck of the woods.