A Little Frost Is Normal — Solid Ice Is Not
It's important to separate normal frosting from a real freeze-up. In our damp Lower Mainland winters, an outdoor heat pump frosts up regularly — that's expected — and clears itself with a periodic defrost cycle. Light frost that comes and goes is healthy operation, not a fault.
What's not normal is a unit encased in thick, solid ice that doesn't clear, an indoor coil that frosts and ices (you may see ice on the copper lines or inside the air handler), or a system that ices up, melts, floods the drain, and refreezes in a cycle. When ice builds faster than the unit can melt it — or melts all at once and overwhelms the drainage — you get the frozen-and-leaking situation.
The leak and the freeze are two sides of the same problem: ice accumulates, then becomes a flood of water when it finally melts.
Why a Heat Pump Freezes Up
Restricted airflow is the most common cause. A clogged air filter, blocked return air, or a dirty indoor coil starves the system of airflow, dropping coil temperature until it ices over. This is the cause most likely to be DIY-fixable.
Low refrigerant lowers coil temperature below freezing and causes persistent icing — and because it stems from a leak, it needs a certified technician.
A failed defrost cycle means the outdoor unit can't melt its own frost, so ice simply keeps building. The defrost control, sensor, or reversing valve may be at fault.
A stuck or failed fan on the outdoor unit stops air moving across the coil, accelerating ice buildup.
A buried or blocked outdoor unit — packed with snow, leaves, or set too low to the ground — can't breathe or drain, so it freezes. And simply running cooling mode when it's too cold out can freeze the coil, though that's less common with heating systems.
Safe Steps You Can Take
If your unit is frozen and leaking, start by turning it off at the thermostat and letting it thaw. Running a frozen heat pump strains the compressor and can cause damage, so don't force it.
You can switch the system to fan-only mode (if available) to help circulate air and gently speed thawing, or simply turn it off and let the ice melt naturally — never chip, hammer, or pry at the ice, as that can puncture the coil and cause an expensive refrigerant leak. Keep towels and a bucket ready for the meltwater so it doesn't damage floors or pool near electrical parts.
While it thaws, change the air filter if it's dirty and clear snow, leaves, and debris from around the outdoor unit so it can breathe and drain. If the unit refreezes after thawing, or never fully thaws, that points to a deeper fault — refrigerant, defrost, or fan — that needs a technician. Don't keep cycling a unit that won't stay thawed.
Why BC Winters Cause This
Greater Vancouver's particular winter — cold, but rarely deep-freeze cold, and very damp — is almost tailor-made to frost heat pumps. Air that's near freezing and saturated with moisture deposits frost readily on the outdoor coil, so local units cycle through defrost frequently. When any part of that defrost process falters, ice gains the upper hand fast.
Wet snow is another local factor. A heavy, wet snowfall can pack around or on top of an outdoor unit, smothering airflow and trapping meltwater that then refreezes. Keeping the unit cleared after snowfalls genuinely helps prevent freeze-ups.
And because our winters hover right around the frost line, the melt-and-refreeze cycle is common: ice melts during a milder afternoon, floods the drain, then refreezes overnight — producing both the leak and the ice that homeowners notice together.
Call CanroHeat to Fix the Root Cause
Heat pumps for GasBoilers.ca are serviced by our parent company, CanroHeat, with technicians across Greater Vancouver. If your heat pump keeps freezing and leaking after you've thawed it, changed the filter, and cleared the outdoor unit, the underlying cause needs a professional — call 604-359-1081.
A technician will pinpoint why it's freezing: checking refrigerant levels, testing the defrost control and sensors, inspecting the fan and reversing valve, and confirming airflow. Fixing the root cause stops the freeze-leak cycle for good and protects the compressor from the strain of running iced. Don't keep fighting the ice on your own — call 604-359-1081 to get it solved.