Why Has Your Home's Heat Pump Become Frosted Over?

outdoor ac unit

If you heat with a heat pump, you are probably familiar with occasional frost or even light ice on the coil. This is normal, and the heat pump is designed so you can defrost it. However, if you ever see your heat pump encased in ice, that's another story altogether. It means there's a malfunction, and you need to have your frosty heat pump serviced right away.

Following is a troubleshooting guide for your ice-encrusted heat pump.

Defrosting Cycle

When a heat pump gets frost on the coil, the reversing valve comes on, sending the equipment into defrosting cycle (which is actually the air conditioning mode) and shutting off the outdoor fan. That allows the refrigerant, which in heating mode has been absorbing heat from the outside air, to circulate through the coil, and because it's warm (in A/C mode, it has been absorbing heat from inside the house) to defrost the ice.

Simultaneously, the second stage heating comes on and heats the house, so that cold air isn't blowing through the vents. After a few minutes, the defrost mode switches off and the heat pump goes back into heating mode.

Too Much Ice

If you see your heat pump encased in ice, then you know one of the following things has probably happened. You will need professional help to fix any of these problems:

  • Defrosting cycle not working properly
  • Timer malfunction
  • Reversing valve sticking
  • Low refrigerant
  • Outdoor fan motor bad
  • Reversing valve solenoid coil malfunction
  • Unit has settled or sunk so moisture can't drain

Some causes for heat pump icing that you can fix:

  • Coil blockage with leaves or snowdrift
  • Gutter leaking melted snow or rain onto unit
  • Freezing rain

Here are some possible fixes:

  • Turn the unit off, remove ice with a garden hose
  • Fix your gutters
  • Deflect snow or rain from unit
  • Elevate the unit so moisture can drain away

Do not pick at ice with a sharp object, as you may harm the heat pump parts.

For help resolving your frosty heat pump problems, call us at Avery Heating and Air Conditioning. We serve Blowing Rock, Boone, and Marion.

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