A heat pump that cycles on and off all the time is certainly inefficient. More important, if the issue is left unaddressed, the heat pump may soon fail, resulting in unexpected and potentially expensive repairs.

What causes heat pump short cycling? And how can you get to the root of the problem to avoid further issues?

First, What Is Short Cycling?

Heat pumps, like all heating and cooling systems, occasionally malfunction. One of the most common HVAC issues homeowners face is short cycling. This occurs when a heat pump (or air conditioner or heater) turns on and off repeatedly, sometimes for just a few seconds.

How to Tell if Your Heat Pump Is Short Cycling

A short-cycling heat pump will cycle on and off much more frequently than usual. That might mean your heat pump kicks on every ten to fifteen minutes, every five minutes, or every few seconds. Unfortunately, diagnosing the problem isn’t as clear-cut as expected.

Just because your heat pump comes on every 10 minutes doesn’t mean it’s short cycling. There’s no set length of time for a complete round of heat pump cycling on and off to complete.

How long it runs varies based on several factors, including:

  • The type of heat pump
  • The outdoor temperature
  • The indoor heat setting
  • The unit size, age, and condition

That said, most homeowners know if their heat pump is cycling more often than usual. If your heat pump turns on and off every few seconds, there’s a problem.

For help troubleshooting a short-cycling heat pump, contact your local One Hour Heating & Air Conditioning® for service.

How Often Should a Heat Pump Cycle On and Off?

As noted above, heat pumps have no set cycle time, and the bigger the difference between indoor and outdoor temperatures, the longer and more frequently they need to run. In most cases, however, heat pumps should turn on no more than two or three times in an hour.

Related: Where Do Heat Pumps Work Best?

What Causes Short Cycling?

Short cycling in heat pumps and other HVAC systems is usually due to one—or more—of these common problems:

  • Clogged or dirty air filter
  • A thermostat issue
  • A refrigerant leak 
  • A failing compressor
  • An electrical issue
  • Dirty coils

We’ll walk through each of these in our heat pump short cycling troubleshooting tips below.

Heat Pump Short-Cycling Troubleshooting

In most cases, heating and cooling issues boil down to bad temperature readings, poor airflow, or mechanical problems like refrigerant leaks or clogged coils. Heat pumps are no different, which makes a precursory inspection by homeowners relatively easy.

A Clogged Air Filter

If your heat pump is short-cycling in heat mode only, a clogged filter is the most likely culprit!

A dirty air filter restricts airflow, causing the unit to run longer or turn on more frequently to maintain a comfortable indoor air temperature. Severely clogged filters may cause your fan motor to overheat, forcing repeated automatic shutoffs—short cycling.

Replace the filter in your HVAC stack every two to three months and check your air filter for signs of built-up dirt and debris whenever your heat pump is kicking on and off too often.

A Refrigerant Leak

Like traditional central air conditioning units, heat pumps use refrigerant to transfer heat energy. Whether caused by wear and tear, manufacturing defects, or corrosion, refrigerant leaks reduce efficiency, which may trigger short cycling. Always rely on a professional HVAC technician to deal with confirmed or suspected leaks.

A Frozen Evaporator Coil

Evaporator coils remove heat and humidity. In cooling mode, they remove heat energy and excess moisture and transfer the energy outside. A faulty blower motor, low refrigerant levels, or poor airflow can all lead to a frozen coil.

If your heat pump is short cycling in cooling mode only, a frozen evaporator coil is likely the issue. You can turn the system off for 24 hours to thaw the coil and then turn it back on, but you’ll still need to determine the underlying cause.

An Electrical Issue

Heat pumps are powered by electricity, so corroded wires, loose connections, or improper heat pump installation may be the reason your heat pump is short cycling. Faulty electrical wiring and failing circuit breakers are best handled by a professional.

Get Your Heat Pump Back in Sync

Short cycling might be a common issue, but that doesn’t mean it’s something to ignore. With help from the experts at your local One Hour Heating & Air Conditioning®, you can lengthen the working lifespan of your heat pump and enjoy year-round whole-home comfort.

Our technicians are heat pump experts, and we provide fast, reliable service you can count on, no matter what.

Find our location near you or call 800-893-3523 to schedule an appointment today!