Troubleshooting Your Heat Pump

Heat pumps do operate somewhat differently than a traditional system. So how do you begin heat pump troubleshooting? And are there issues you can fix yourself?

In some cases, there are issues you can prevent and problems you can solve on your own when you are aware of the heat pump troubleshooting steps. Here is a list of the most common problems we see with heat pumps, possible causes and what to do next. Of course, if you are uncertain of the issue, we recommend that you contact your HVAC specialist and schedule an appointment.

During the cold winter months, your heat pump’s outside unit will sometimes be covered with a coating of frost on the sides, or even light ice. This is perfectly normal. Every so often, the unit will go into defrost mode to remove that frost.

However, if the top of the unit has a heavy coat of ice, the coils are encased in ice, or the entire unit is covered with a thick sheet of snow and ice, this indicates a problem. All that ice prevents the transfer of heat between the refrigerant and the outside air, and impedes the operation of the heat pump. If you don’t take care of it soon, you could damage the unit beyond repair. Ice in the coils can damage the sensitive fins, the fan blades, and eventually lead to compressor failure.


  • The unit is not defrosting. Under normal conditions, your heat pump periodically switches to defrost mode for a few minutes, which heats up the outdoor coils enough to melt any frost and light ice that has accumulated. If the unit is not defrosting, ice can build up in a hurry. Defrost issues can be caused by faulty relays, controls, or sensors. There could also be a problem with the reverse valve that switches the unit from heat to air conditioning mode.
  • Outdoor unit is blocked. If piles of snow have accumulated around the outdoor unit, the impeded air flow can cause more icing.
  • Water is leaking onto the unit. Water constantly dripping on the unit from leaky gutters can gradually form a layer of ice on top.


Actually, let’s start with what you should NEVER do: use a hard or pointy object to try to chip away the ice! Those fan coils are very delicate and can easily be damaged. Instead, use water from a hose to melt the ice.

  • Remove and debris or snow that may be blocking the unit.
  • Check for leaking gutters that may be dripping water onto the unit, and repair them.
  • Call your HVAC service tech to troubleshoot defrost issues.