By Mario Vaghei, General Manager, Aire One Peel Heating & Cooling · Published August 4, 2026 · Facts verified August 4, 2026
Heat pumps behave differently from the furnaces and air conditioners most Peel Region homeowners grew up with, and a large share of “my heat pump is broken” moments are the machine doing exactly what it was designed to do. This guide starts with those false alarms, walks the free checks, decodes the real failures, and names who handles each one, and when a visit is genuinely needed, our line runs 24/7 with no after-hours charge, backed by the same team behind every heat pump installation we do.
In this guide
The two “failures” that are normal · The free checks · Symptom to likely cause · DIY or technician · FAQ
Short answer
A heat pump that seems broken is often in defrost mode, a normal winter cycle where heating pauses, the outdoor fan stops, and steam rises for a few minutes; real failures usually trace to thermostat settings, a tripped breaker, a clogged filter, a snow-buried or ice-locked outdoor unit, or the refrigerant circuit.
The settings, filter, breakers, and snow clearing are yours; solid ice, a stuck reversing valve, and anything refrigerant belongs to certified 313A or 313D mechanics through our 24/7 line at 905-564-8545.
The two “failures” that are completely normal
Before assuming your heat pump not working means a breakdown, rule these two out first. Defrost mode is the biggest false alarm in the heat pump world: in cold weather, frost builds on the outdoor coil, and every so often the system pauses heating, stops the outdoor fan, briefly runs in reverse, and melts it off, which produces a cloud of steam, a change in sound, and a few minutes of cooler indoor air before normal heating resumes. Nothing is wrong; that is the machine maintaining itself, several times a day in damp cold. The second false alarm is the supply air itself: a heat pump delivers air noticeably cooler than a gas furnace’s blast, warm enough to heat the house steadily but cool enough against your skin to feel lukewarm, and new owners in their first Mississauga winter routinely report it as a fault. The test is the thermostat, not your hand: if the house is holding its set temperature, the “cool air” is normal operation.
The free checks before you call anyone
Most cases of a heat pump not working are solved by these quick, no-cost checks. Five checks, all safe, all free, and between them they close a real share of heat pump calls.
| Check | What to do |
|---|---|
| 1. Thermostat | Correct mode (heat, not emergency heat), set point past room temperature, fresh batteries |
| 2. Both breakers | Heat pumps have indoor and outdoor breakers; one reset each, and if either re-trips, stop and call |
| 3. Filter | Swap a clogged filter; starved airflow cripples heating and cooling alike |
| 4. Outdoor unit clearance | Clear snow, drifts, and leaves; the unit needs free airflow on all sides and clear drainage below |
| 5. Watch ten minutes | Steam and a pause that resolves on its own was defrost; note what actually happens before calling |
Safe homeowner checks only; the refrigerant circuit, reversing valve, and defrost controls belong to a certified refrigeration mechanic.
Safety note: if the outdoor unit is locked in solid ice, switch the system off and let it thaw; never chip or pry ice off the coils, because the fins bend and the refrigerant lines behind them are one slip away.
An electrical burning smell or a breaker that re-trips after one reset means off at the breaker and a call, not another reset, and refrigerant work is regulated in Ontario under O. Reg. 463/10, certified 313A or 313D refrigeration mechanics only.
Symptom to likely cause
Use this table to match a heat pump not working symptom to its most likely cause. Match what the system is doing below; two of the rows resolve into the normal-operation column, which is exactly why they lead this page.
| Symptom | Likely cause | Urgency |
|---|---|---|
| Steam, a pause, outdoor fan stopped, then recovery | Defrost mode | Normal, none |
| Air feels lukewarm but the house holds temperature | Normal heat pump supply temperature | Normal, none |
| No heating or cooling at all | Mode, breakers, or a failed component | Checks first, then same day in winter |
| Outdoor unit locked in solid ice | Defrost failure or water draining onto the unit | Off, thaw, and book |
| House losing temperature in a deep freeze | Auxiliary heat not engaging, or output past the design limit | Same day |
| Cooling in heat mode, or heating in cool mode | Stuck reversing valve | Book, technician |
Patterns reflect common heat pump behaviour and failure modes; the on-site diagnosis governs. They read the same across Mississauga, Brampton, Etobicoke, Milton, Georgetown, Caledon, and Bolton.
What you can fix, when to call, and one honest cold-weather note
One behaviour deserves its own honest paragraph before the split: in a deep cold snap, a heat pump running continuously is usually design behaviour, not failure. Output declines as the outdoor temperature drops, and near the system’s balance point it is engineered to run long and steadily, with the auxiliary heat topping up beyond that; the symptom worth a call is a house actually losing temperature, or auxiliary heat running constantly in mild weather and inflating the bill. Everything else splits cleanly below.
| Yours to do | Certified technician only |
|---|---|
| Thermostat mode, set point, batteries | Refrigerant circuit, per O. Reg. 463/10 |
| One reset per breaker, indoor and outdoor | Reversing valve and defrost control diagnosis |
| Filter check and replacement | Auxiliary heat and control wiring |
| Snow and debris clearing, off-and-thaw for ice | Panel or wiring faults, ESA-licensed electrician |
The split per Ontario’s refrigerant handling rules; when in doubt, the item belongs on the right side.
If your heat pump is new to you and this page keeps answering “that is normal”, that is the adjustment period every convert goes through, and our comparison of the difference between a heat pump and a furnace covers the behavioural differences in full. For real repairs, the questions worth asking any company are who touches the refrigerant, certified 313A or 313D mechanics is the only right answer, and whether after-hours carries a surcharge; ours does not, our line runs 24/7 availability-based, and if a diagnosis on an older unit opens the replacement question, a free estimate prices a new heat pump installation beside the repair.
Is your heat pump broken, or just being a heat pump? 20 seconds
Two questions, same logic as the tables above.
What is happening?
The triage needs JavaScript; the symptom table above gives the same answers.
How we know this
Compiled by Mario Vaghei from cold-climate heat pump operating behaviour, manufacturer service documentation, and Ontario refrigerant handling requirements under O. Reg. 463/10, verified August 2026. [INSERT AIRE ONE PEEL DATA: share of winter heat pump service calls that turned out to be normal defrost operation with no fault found, with the N and window.]
Checks done, defrost ruled out, and it is still not right?
One call, 24/7, availability-based, no after-hours charge, written diagnosis, certified 313A/313D mechanics on the refrigerant side. Aire One Peel Heating & Cooling, 1625 Courtneypark Dr E, Mississauga, ON L5T 1V9.
Heat pump not working: frequently asked questions
Why is my heat pump not heating?
Start with the free suspects: the thermostat in the wrong mode, a tripped breaker on either the indoor or outdoor unit, a clogged filter, or an outdoor unit buried in snow or locked in ice. Past those, the causes move to the refrigerant circuit, the reversing valve, or a failed component, which are certified-technician territory, and in winter a genuinely dead system is a same-day call.
Why is my heat pump blowing cool air in heat mode?
Two normal explanations come first: defrost mode, which pauses heating for a few minutes while steam rises outside, and the heat pump’s ordinary supply temperature, which is cooler than a furnace’s blast yet warm enough to hold the house at its set point. If the house is genuinely losing temperature rather than merely feeling less blast-furnace-like, the real suspects are the reversing valve or the refrigerant charge.
Is it normal for a heat pump to steam and stop in winter?
Yes: that is the defrost cycle, where the system pauses heating, stops the outdoor fan, briefly reverses, and melts accumulated frost off the outdoor coil, producing a visible cloud of steam and a change in sound for a few minutes. It can repeat several times a day in damp cold, resolves on its own, and only becomes a fault when ice builds into a solid block despite it.
Why is my heat pump covered in ice?
Light frost that comes and goes is normal and defrost handles it; a solid ice block means the defrost cycle is failing or water is dripping onto the unit from a gutter or roofline and refreezing. Switch the system off and let it thaw rather than chipping at the coils, fix any drainage landing on the unit, and book a visit, since defrost controls sit on the technician side of the line.
Why does my heat pump run constantly in cold weather?
Usually because it is supposed to: heat pump output declines as the outdoor temperature drops, and near the system’s balance point it is designed to run long and steadily, with auxiliary heat topping up in the deepest cold. The behaviours worth a call are a house actually losing temperature, or auxiliary heat running constantly in mild weather, which shows up as a jump in the electricity bill.
Who repairs heat pumps in Mississauga?
A licensed HVAC company whose refrigerant work is done by certified 313A or 313D refrigeration and air conditioning mechanics, which Ontario’s O. Reg. 463/10 requires for anything touching the refrigerant circuit; electrical panel faults route to an ESA-licensed electrician instead. Aire One Peel services heat pumps across Peel Region 24/7 at 905-564-8545 with no after-hours charge and a written diagnosis.
Final verdict
A heat pump not working the way you expect is often a heat pump being a heat pump: steam and a pause is defrost, lukewarm-feeling air with a steady house is normal supply temperature, and a long continuous run in a deep freeze is design behaviour near the balance point. Run the five free checks for everything else, switch off and thaw for solid ice, and for the real failures, the reversing valve, the defrost controls, the refrigerant circuit, our line answers 24/7 at 905-564-8545 with no after-hours charge, certified 313A/313D mechanics on the sealed side, and the honest comparison of repair against a new heat pump installation in Mississauga whenever the unit’s age earns it.
Sources and references
O. Reg. 463/10, Ozone Depleting Substances and Other Halocarbons, Government of Ontario Skilled Trades Ontario, 313A and 313D refrigeration and air conditioning mechanic trades Natural Resources Canada, cold-climate air source heat pumps Electrical Safety Authority (ESA), licensed electrical work requirements
Mario Vaghei
General Manager, Aire One Peel Heating & Cooling
Mario compiled this troubleshooting guide from cold-climate heat pump operating behaviour, manufacturer documentation, and Ontario refrigerant regulations, verified in August 2026.