Why Is My Heat Pump So Loud?


Noisy heat pump? Don’t freak out. Though some sounds could indicate a heat pump problem, many sounds are normal. Here’s how to differentiate between the two…

Normal Heat Pump Noises

Some noise is normal during the operation of your heat pump. Most of these will be on the mild side, such as:

  • Whooshing
    When heat pumps go into defrost mode, they make a whooshing sound for a couple of seconds, followed by a slightly louder compressor sound. Heat pumps are often louder in the wintertime when they work the hardest.
  • Rattling/Vibrating
    Rattling reminiscent of an off-balance washing machine or back-peddling flutter at shutdown and start up is normal.
  • Clicking/Tapping
    This is another normal sound to hear at startup/shutdown.
  • Humming/Buzzing
    A slight buzzing from the outdoor unit, even when it’s not running, could be from the reversing of the valve solenoid coil. This low-voltage valve is louder in some systems than others, and in most cases this noise is normal.
  • Squeal
    If your system has always had a high-pitched squeal at startup, this could be normal.

Worrisome Sounds

When operating your heat pump, loud noise could indicate a problem:

  • Metal Hitting Metal
    Fan blades may be hitting chunks of ice or lose wires/components in the system. Turn off the system ASAP before you ruin the blades, overburden the motor, or cause damage to other system components as blades break.
  • Vibrations/Rattling
    Frequent vibrations/rattling that grows worse over time could indicate loose hardware/parts, refrigerant piping that is strapped too tightly, or unsecured ductwork. There could also simply be a couple of loose screws in the cover panel. But some systems are just noisier than others, growing increasingly so with age, and only replacement will solve this scenario.
  • Clanking
    Typically a frayed/loose fan belt.
  • Popcorn/Tumbling Rocks
    If the compressor is receiving liquid refrigerant, this strange sound will be heard, and should be remedied immediately. There are a number of potential causes for this scenario.
  • Gurgling Noises
    These are indicative of a low refrigerant charge, which can severely impact performance.
  • Grinding
    This sound is usually a precursor to shrieking, and typically indicates a lack of lubrication or dirty components.
  • Shrieking
    Uncomfortably loud shrieking noises could point to a bad compressor that is under high pressure, dangerous, and should be shut down immediately. Dirty motor bearings can also be very noisy, and are a sign of a motor that will soon be in need of replacement.
  • Hissing
    This almost always indicates a large refrigerant leak, and a system that will be down in the very near future.
  • Squeal
    If you hear a high-pitched squeal sound, and you’ve never noticed it before, this could be a sign of a motor going bad.
  • Humming/Buzzing
    If your system buzzes, but does not run, this could indicate a stuck relay/contact, faulty capacitor or motor issues.

Don’t let your heat pump become another one of the broken appliances you’ve been living with. Address problems now to avoid greater expense later. Investigate those interesting heat pump noises with the help of Aire Serv today.