Quick answer
If your heat pump is covered in snow, switch the system off or to emergency heat, then clear the snow by hand or with a soft brush from around, above and beneath the unit until it has 30–60 cm of open space on every side. Never chip ice or use a shovel on the fins. Turn it back on and let the defrost cycle melt what is left.
A heat pump covered in snow needs clearing the same day, and the job takes ten minutes with a gloved hand and a broom. The outdoor unit heats your house by pulling air through its coil. Snow drifted against that coil, capping the top or packed in underneath cuts the airflow, and the unit responds by icing up. A dusting on the cabinet or a thin white frost on the coil is different: that is normal, and the defrost cycle deals with it.
How to clear snow off a heat pump without damaging it
- Turn the system off at the thermostat, or switch to EM HEAT if you have backup heat, so the fan cannot start while your hands are near it.
- Brush loose snow off the top and away from the coil with a soft broom or your gloved hand, working in the direction of the fins.
- Dig out the sides and back to the clearance in the installation manual, typically 30–60 cm, and more in front of the fan where the air blows out.
- Clear underneath until you can see daylight below the base pan and the drain openings are free.
- Shovel a path for the meltwater so it runs away from the unit instead of pooling and freezing under it.
- Turn the system back on and watch one defrost: steam, a whoosh and water dripping from the base are all normal.
What never to do: chipping ice, shovels on the fins, covers
- Do not chip, pry or hammer at ice. The coil is thin aluminium fins over copper tubing that holds the refrigerant, and one slip with a screwdriver or ice pick punctures it.
- Do not use a shovel blade or a stiff brush on the fins. Bent fins block airflow permanently.
- Do not pour boiling water over the unit. The runoff refreezes in the base pan, and the sudden heat is hard on cold plastic and metal.
- Do not reach into the fan guard with the power on.
- Do not wrap the unit in a tarp or winter cover while it is in service. A heat pump runs all winter and has to breathe.
Solid ice is a separate problem from snow, with its own steps in how to defrost a frozen heat pump.
Why a buried base pan turns into a block of ice
Blocked airflow and blocked drainage feed each other. With less air crossing the coil, its surface runs colder, frost builds faster and the unit goes into defrost more often. Each defrost melts that frost into water, which is supposed to fall through the openings in the base pan and drain away. When the pan is sitting in snow the water has nowhere to go; it refreezes in the pan, and each cycle adds another layer.
After a day or two the ice has climbed from the base into the bottom rows of the coil and up to the fan. That is when the damage starts: fan blades strike the ice, and ice expanding between the tubes can crush them. A unit in this state heats poorly and leans on its backup, which is one answer to why a heat pump ices up.
Prevention: a stand above the snow line and a spot clear of roof drip
The lasting fix is height. A heat pump should sit on a stand or wall bracket that holds the base pan above the deepest snow that side of the house normally sees, with open space beneath for meltwater to drip clear. A unit set on a pad at ground level, the way an air conditioner is, gets buried by the first heavy snowfall or by the shovelled pile from the walkway. Raising an existing unit onto a stand is a routine job and is quoted in writing, since it can mean extending the line-set.
- Keep the unit out from under roof drip lines and eavestrough overflow. Water dripping from the roof edge freezes onto the top of the cabinet and into the fan.
- On open rural lots in Caledon, Flamborough or north Burlington, wind-driven drifts bury a unit faster than snowfall alone would; check it after every windy night.
- Never aim the snowblower chute at the unit or pile shovelled snow against it.
- A manufacturer-approved snow hood, or a small roof well above the unit, keeps snow off the top without restricting airflow. A cover that wraps the cabinet does the opposite.
- After freezing rain, look at the fan: if the blades are frozen in place, switch to backup heat until the ice lets go.
Call a technician now if you see any of these
- The fan is hitting ice, or you hear scraping or a rhythmic knock.
- The coil is still encased in ice several hours after you cleared the snow.
- Fins are crushed flat over a wide area or the fan guard is bent in.
- The outdoor breaker has tripped or the thermostat shows a fault.
- The unit runs but the house will not hold temperature without backup heat.
While you wait, EM HEAT or the gas furnace on a hybrid system keeps the house warm. A diagnostic visit is $90–$150 and goes toward the repair; most heat pump repairs are $150–$800.
ZK Mechanical repairs ice and defrost faults and re-mounts units that were set too low, from the Burlington shop out to Milton, Georgetown and Caledon. The heat pump repair page explains the visit, the heat pump topic hub covers the related winter questions, and you can book online or call (647) 801-1252.