The heat pump gained popularity in the 1950s in Japan and the United States. Heat pumps can extract heat from various sources, such as environmental air, exhaust air from a building, or from the ground. Heat pumps transfer heat from outside the structure into the air inside. Initially, heat pump HVAC systems were only used in moderate climates, but with improvements in low temperature operation and reduced loads due to more efficient homes, they are increasing in popularity in cooler climates.
AC air handler buzzing sounds. Do you hear a buzzing sound when you turn on the thermostat? The only thing that comes on in the house when you turn on the thermostat is the fan relay and fan in the air handler or furnace. Try switching the thermostat HEAT/COOL switch to OFF. Then switch the fan switch from AUTO to ON. The fan (only) should come on. If the air handler makes a buzzing sound, it probably has a bad fan relay or, more likely, blower fan.
I originally took off one star because of the SNAFU with getting the part ordered. When Alberto called me on the phone he admitted the person had "gotten busy with other things" and apologized. THAT was taking the high road and I was impressed by that. Sadly, for reasons I won't guess at, Alberto has decided to take the low road in his comments and imply that they got the part as quickly as possible. Well, we called at 2:30 so did someone spend six and a half hours finding the part?? That seems very doubtful.