Air-Source Heat Pumps: Dealing With A Frozen CoilAir-source heat pumps ice up occasionally during a typical winter in Indianapolis. Homeowners who look at their heat pump and see a light layer of frost should not be overly concerned, as a heat pump’s defrost cycle should be able to remove minor frosting. When a heat pump has a lot of ice in and around it, however, you should turn the unit off and try to determine what’s causing the unit to freeze.

Defrosting heat pumps

Heat pumps come equipped with a defrost cycle. On older models, this unit is typically triggered by a timer. Newer, more efficient designs take into account the temperature of the unit and surrounding air to determine when the defrost cycle should be run.

Most of the time, the defrost cycle will prevent ice from forming. However, some problems create more ice than a standard defrost cycle can handle. Of course, a malfunctioning defrost cycle also will prevent a unit from working properly in the winter. Some of the common causes of ice buildup on air-source heat pumps include:

  • A broken defrost thermostat or timer
  • A sticking reversing valve
  • A defective reversing valve solenoid coil
  • A faulty outdoor fan motor
  • Low levels of refrigerant
  • Water buildup in an unlevel unit
  • Leaves or snow blocking the airflow
  • A leaking gutter that drips water
  • Freezing rain

When to call a professional

Homeowners can remedy some minor issues, such as a leaky gutter or debris around the outside unit, on their own. For most problems, though, homeowners should consult a professional technician. Heat pumps can be hazardous to people who are not formally trained to work on them or certified to work with refrigerant, so homeowners should refrain from attempting to solve more serious problems themselves.

Families in the Indianapolis area should contact Mowery Heating, Cooling and Plumbing for all their home-comfort needs. With more than 40 years of experience, our technicians have the experience and knowledge needed to quickly repair frozen air-source heat pumps.

Our goal is to help educate our customers in Brownsburg, Indiana and surrounding areas about energy and home comfort issues (specific to HVAC systems). 

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