Heat Pump Not Heating: Where to Start
When a heat pump stops heating well, the cause is not always mechanical. A share of lost capacity is simply fouling. This page explains what professional cleaning can correct, what it cannot, and how to tell the difference before you call.
What Climeo can do
A guide for Greater Montreal homeowners and building managers whose wall-mounted heat pump heats poorly, or not at all, as the cold season starts.
- Accessible indoor coil cleaning
- Blower wheel cleaning
- Filter service
- Pan flush and drain path check
- Scope confirmation before any work begins
Call a licensed technician first if
- Burning smell, smoke, or electrical arcing sounds
- The unit repeatedly trips the breaker
- A solid block of ice is trapping the outdoor fan
Before requesting a visit
Tell us the brand and unit type, how long heating has been weak, and whether the outdoor unit is iced. A photo of both the indoor and outdoor units helps us confirm scope before dispatch.
Maintenance-related causes
- Saturated filters restricting airflow
- Fouled indoor coil limiting heat exchange
- Blower wheel loaded with dust
- Outdoor unit blocked by snow or leaves
- Clogged condensate drain
Important to understand
- Cleaning does not fix low refrigerant, a failing compressor, a stuck reversing valve or a control-board fault. That work requires a licensed refrigeration technician — Climeo does not perform it.
- If the unit will not start, trips the breaker, smells like burning, or is locked in solid ice, treat it as a mechanical or electrical fault and call a licensed technician before scheduling any cleaning.
What cleaning can fix — and what it cannot
A heat pump that stops heating well is not automatically a mechanical failure. A share of lost heating capacity comes from fouling: a blocked indoor coil, saturated filters, a blower wheel packed with dust. The unit runs, but it can no longer move heat properly.
The other causes — low refrigerant, compressor, reversing valve, control board, failed sensor — have nothing to do with cleanliness and require a licensed refrigeration technician. Climeo does not perform that work and does not claim to.
- Saturated filters: reduced airflow and heating capacity
- Fouled indoor coil: less heat exchange
- Loaded blower wheel: sharply reduced airflow
- Outdoor unit blocked by snow, ice or leaves
- Clogged drain causing water or ice build-up
Normal frost vs abnormal ice on the outdoor unit
In a Montreal winter a layer of frost on the outdoor unit is normal — the system periodically runs a defrost cycle and clears it. What is not normal is a solid block of ice that persists, traps the fan, or fully encases the coil.
If ice returns immediately after a defrost cycle, or the unit is locked in ice, the problem is mechanical or drainage-related, not a cleaning issue.
What you can safely check yourself
These checks need no tools and carry no electrical risk.
- Is the mode actually set to heat, with the setpoint above room temperature?
- Are the filters visibly loaded? (pull them and hold them up to the light)
- Is the outdoor unit clear — snow, ice, leaves, obstructions within 60 cm?
- Is airflow at the indoor unit weak compared with summer?
- Is there a musty smell when heating starts?
Do not attempt this
These actions are dangerous or cause expensive damage.
- Never chip ice off with a sharp tool — coils puncture very easily
- Do not open electrical panels or bypass any safety
- Never handle refrigerant — that is licensed work
- Do not pour boiling water over the unit
Questions about this service
Why does my heat pump run but not heat?
When the unit runs without producing heat, common causes are airflow that is too low (loaded filters and a fouled coil), a defrost cycle that cannot keep up, or a refrigerant problem. The first group is corrected by cleaning; the second requires a licensed technician.
Can cleaning really improve heating?
Yes, when the lost capacity comes from fouling. A blocked coil and saturated filters genuinely reduce heat transfer. If the cause is mechanical, cleaning will not change it — we say so before starting.
Is frost on the outdoor unit normal in winter?
A layer of frost is normal; the system defrosts periodically. A persistent solid block of ice, or ice jamming the fan, is not.
Can I remove the ice myself?
Never use a sharp tool or boiling water — coils puncture easily and repairs are expensive. Clear only loose snow around the unit, by hand.
How often should a year-round heat pump be cleaned?
Once a year is the standard manufacturer recommendation for a unit used for both heating and cooling.