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Why Is My Heat Pump Making Loud Strange Noises?

Heat pumps do make strange loud noises especially in the wintertime. It’s just the nature of the beast. i.e., heat pumps have reversing valves that reverse (or shift) the flow of refrigeration between the heating and cooling modes. This occurs every time the unit goes into the “defrost cycle”.

When this shifting occurs, there is a “swooshing” sound, which usually lasts for several seconds. The “swooshing” sound is sometimes followed by a somewhat louder compressor noise as it shuts down to allow the refrigerant pressures to equalize. All these noises are perfectly normal.

If you hear a metal to metal sound or a persistent “thumping” sound, check the fan blade of the compressor to see if the blade can be hitting something (ice, wire, twig). Shut the unit off, immediately as this not only will ruin the fan blade by throwing it out of balance, but if allowed to persist, may ruin the fan motor as well.

There is always “vibration” noise. Sometimes it’s only a matter of installing (or replacing) isolation pads, or the refrigerant lines are strapped too tight. Other times it can be the unit itself and cannot be eliminated.

If any of the following are occurring, be sure to call us and have us come take a look. It could be something simple or something that needs to be fixed right away to prevent permanent damage to the unit.

  • Low refrigerant charge (gurgling noise)
  • Defective reversing valve-makes hissing sound
  • Defective compressor valve
  • Defective motor
  • Out of balanced or bent fan blades
  • Buzzing contactor or solenoid coil
  • Loud compressor
  • Loud unit