Often overlooked but telling indicators: what your heat pump is trying to tell you before it’s too late
In the world of residential HVAC in Laval, it’s common for homeowners to ignore or underestimate certain warning signs that their wall-mounted heat pump is nearing a failure. And yet, these subtle symptoms can point to underlying technical problems that may worsen right in the middle of winter. At AirGreen, we’ve identified seven quiet—but critical—signals you should pay close attention to. Spotting them early can help you avoid a major breakdown, losing your heating when it’s freezing, and facing high repair bills.
1. The air blowing out is lukewarm… even in heating mode
This first symptom is often misunderstood. If your wall-mounted heat pump is blowing lukewarm or slightly cool air in heating mode, it doesn’t necessarily mean the system has failed. It could indicate:
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Low refrigerant levels due to a slow leak.
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A faulty temperature sensor that’s preventing the compressor from engaging.
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A worn-out compressor that can no longer generate enough pressure.
In all cases, heat output is compromised, and energy efficiency drops immediately.
2. New or unusual noises
A metallic clinking, a high-pitched whistle, or a repetitive thumping can signal:
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An unbalanced fan wheel.
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A worn-out fan motor.
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Abnormal compressor vibration.
These issues should never be ignored—they are often the sign of an imminent mechanical failure.
3. The outdoor unit gives off a strange smell
A smell like burning, hot plastic, or mildew around your outdoor unit is a red flag that something is overheating or that electrical insulation is failing. This might be caused by:
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An overheating contactor.
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Water infiltration reaching electrical components.
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A malfunctioning control board.
These problems are common in units exposed to the harsh winter conditions we get in Laval.
4. The defrost cycle runs too often… or not at all
A defrost cycle that kicks in too frequently, or not at all, means there’s a problem with the electronic control system. This imbalance can lead to:
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Ice building up on the outdoor unit, blocking airflow.
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The compressor overworking to try and compensate for the loss of heat.
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A complete heating failure if the unit becomes fully frozen.
5. An unexplained spike in your electricity bill
A sudden jump in electricity usage during winter—without any change in your habits—can reflect a loss in your heat pump’s efficiency. This often happens when:
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The compressor is running in overload mode.
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There’s been a partial refrigerant leak.
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The unit is clogged with dust and debris (filters or coils).
At AirGreen, we perform detailed energy audits to catch these issues early.
6. Error codes appear intermittently
Many newer wall-mounted heat pump models (e.g., Fujitsu, Lennox, Gree) show temporary error codes. If these codes flash and then disappear, they may indicate:
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An unstable control board.
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An intermittent short circuit caused by moisture.
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A failing temperature probe.
Never ignore them—these are signs of an unstable system that could completely fail if not addressed quickly.
7. The unit shuts off by itself without warning
An unexpected shutdown, without any tripped safety feature, is often due to:
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An internal thermal protection trigger.
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A pressure imbalance in the refrigerant circuit.
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A control board malfunction that’s misreading data.
This behavior is common in older or poorly maintained units in Laval, especially during cold snaps.
Why these signs should be taken seriously right now
Québec winters leave no room for error. A failing wall-mounted heat pump in January could mean 48 to 72 hours without heat, while you wait for an available technician. At AirGreen, we recommend:
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Preventive maintenance in the fall, including pressure testing, full cleaning, and electronic inspection.
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Proactive repairs at the first signs of trouble.
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Weekly monitoring of your system, especially during heavy snow or freezing conditions.
AirGreen expertise: prevention, diagnostics, and intervention
Our team is trained to work quickly and efficiently on all wall-mounted heat pump models, with special expertise in Fujitsu, Gree, Lennox, Midea, and more. Our service calls in Laval, Montréal, Longueuil, the North Shore, and the South Shore have helped us build deep experience in early detection of pre-breakdown warning signs.
Every service call includes:
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A full technical diagnosis, including pressure, temperature, and power usage analysis.
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Personalized recommendations, based on the model, age, and condition of your system.
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Complete transparency about what needs urgent repair versus what can wait.
In conclusion: better to act now than repair at -20 °C
A well-maintained wall-mounted heat pump is your best ally against extreme cold. But at the first signs of weakness, call AirGreen. Acting fast can help you avoid major issues, protect your comfort, and extend your system’s lifespan.