The short answer
Check the filter monthly all year, keep the outdoor unit clear of leaves in summer and of snow and ice in winter, and let defrost cycles run – steam and a whoosh are normal. Book professional service; because a heat pump works in both seasons, many makers suggest two visits a year.
Why a heat pump needs care in both seasons
A heat pump uses one refrigerant system to cool in summer and heat in winter, so the same outdoor unit, coil and fan work almost all year. ENERGY STAR advises checking the cooling system in spring and the heating system in fall. For a heat pump, that is the same machine twice, which is why many makers suggest a professional visit before each season. New to heat pumps? Start with our heat pump guide.
Filters, ducted and ductless
ENERGY STAR’s checklist includes heat pumps in its advice to inspect, clean or change air filters once a month. With a heat pump, keep that up through winter as well as summer. A clogged filter makes the system work harder in both modes. See our air filter guide.
Ductless heads have washable filters. ENERGY STAR says to clean them when they are visibly dirty or when the filter light comes on – steps are in our mini-split maintenance guide.
Winter: keep the outdoor unit clear
- Snow. The unit needs air through its sides and out its fan. After a storm, brush snow off and away with a broom, and clear the base so melt water can drain. Do not shovel or plow snow onto it.
- Height. In snowy areas, units usually sit on a raised stand. If yours sits low and keeps getting buried, ask a contractor about raising it.
- Do not chip ice. Never hack at ice with a shovel, screwdriver or ice pick. The fins and coil tubing are thin, and a puncture means a refrigerant leak.
- Ice that will not clear. A light coat of frost that comes and goes is normal. A unit encased in ice that stays after defrost cycles needs a technician. If you need heat meanwhile, switch the thermostat to emergency heat and call.
Watch for roof drip lines
Water dripping from a roof edge or an overflowing gutter onto the outdoor unit can freeze into a heavy cap of ice on the lid and fan. Keep gutters above the unit clear and working. If the unit sits right under a drip line, ask a contractor about a gutter, a diverter, or moving the unit. Do not build your own cover or shelter over it; anything that blocks airflow should be approved by the maker.
Defrost is normal
In cold, damp weather, frost builds on the outdoor coil. The heat pump runs a defrost cycle to melt it: the outdoor fan stops, the reversing valve switches with a whoosh, and you may see steam rising from the unit. It lasts a few minutes, and backup heat may come on briefly indoors. Call a technician if defrost seems constant, or the coil stays iced afterward.
Setbacks and emergency heat
Turning the thermostat down at night or while you are out saves energy with most systems, but heat pumps need care. The Department of Energy’s advice: do not set back a heat pump’s thermostat manually if it causes the electric-resistance heating to come on. A big jump back up in the morning can call for auxiliary heat – electric heat strips that cost more to run. Thermostats built for heat pumps can manage recovery more gently; see thermostat settings.
Emergency heat on the thermostat runs backup heat only. Use it when the heat pump itself has failed or is iced over, not as a cold-weather setting.
Spring and summer
In cooling season a heat pump needs the same care as a central air conditioner: keep about two feet clear around the outdoor unit, rinse the fins gently with the power off, make sure the condensate drain flows, and check the foam insulation on the refrigerant lines. Our AC maintenance guide has the steps.
Professional service
Many makers suggest service twice a year, in spring and fall. A technician should check the refrigerant charge, coils, electrical parts and the condensate drain, and confirm defrost and backup heat work. Only technicians with EPA Section 608 certification may handle refrigerant. Some warranties require proof of maintenance, so keep each invoice.
Sources
- ENERGY STAR: HVAC Maintenance Checklist (checked October 2026)
- U.S. Department of Energy: Energy Savers guide (2011, PDF) (checked October 2026)
- ENERGY STAR: Ductless Heating & Cooling (checked October 2026)
Find an HVAC company near you
Local heating and cooling companies by metro area, listed A to Z with phone numbers, services and emergency options.
Questions
How often should a heat pump be serviced?
Because a heat pump runs in both heating and cooling seasons, many makers suggest professional service twice a year, in spring and fall. Check your warranty terms too.
Is it normal for my heat pump to have ice on it?
A light layer of frost that clears during defrost cycles is normal in cold, damp weather. A thick block of ice that stays, or ice on the lid and fan, is not – call a technician, and do not chip at it.
Should I use emergency heat when it is very cold?
No. The heat pump brings on backup heat by itself when it needs help. Emergency heat is for when the heat pump has failed, and it usually costs more to run.
Can I turn my heat pump down at night?
Only if it will not trigger electric backup heat when it warms back up. The Department of Energy advises against manual setbacks that bring on the electric-resistance heat. A thermostat made for heat pumps can help.
Related guides
Updated October 2026 by the Heating and Cooling editorial team. General information for homeowners, not professional advice – rules and equipment differ. When gas, carbon monoxide, electricity or anyone’s safety is involved, call 911 or your utility. How we write our guides · HVAC glossary