A winter breakdown quickly brought under control
Quebec winters put HVAC systems to the test, and a simple drop in performance can quickly become a major inconvenience. This is exactly what one of our customers in Blainville experienced when their Friedrich wall-mounted heat pump stopped defrosting properly at the height of the cold season. At AirGreen , we quickly responded to diagnose and resolve the problem, restoring indoor comfort within hours.
The context of intervention
Installed on a north-facing brick wall, the Friedrich outdoor unit was exposed to wind and snow accumulation. The customer contacted us after noticing:
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a lack of heat in the house ,
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a more frequent defrost cycle than usual ,
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and an irregular whistling noise when starting.
These signs often indicate restricted airflow or an imbalance in the refrigeration circuit , two common problems on units subjected to extreme winter conditions.
On-site diagnosis
Upon our arrival, our technicians conducted a complete inspection of the Friedrich unit. The main observations were as follows:
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Ice buildup on the lower part of the outdoor coil, indicating partial defrosting.
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Spool slightly clogged with dust and frozen particles.
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Slightly low refrigerant level , confirming a small leak on a flare fitting.
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Defrost sensor showing resistance outside normal values.
Using our digital measuring instruments and a portable charging station, we were quickly able to confirm that the system was suffering from both a micro-leak of R-410A refrigerant and a faulty thermal sensor , preventing optimal defrosting.
Steps of repair
1. Defrosting and preparing the unit
We first defrosted the outdoor coil thoroughly using a defroster safe for aluminum surfaces. Once the ice was removed, we cleaned the heat exchanger grille to maximize airflow.
2. Leak detection and repair
Using an electronic leak detector , we located the problem point on a slightly loose flare fitting . After cleaning, we resealed the joint and applied a tightening torque according to Friedrich specifications.
3. Vacuum drawing and recharging the circuit
A 20-minute vacuum was applied to remove any moisture. The system was then recharged with R-410A at the manufacturer's recommended pressures.
4. Replacing the defrost probe
We replaced the faulty thermal sensor with an original Friedrich sensor , guaranteeing an accurate and efficient defrost cycle even in very cold weather.
Checks and results
After restarting, the Friedrich heat pump displayed optimal performance values :
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Indoor blowing temperature: 32°C ,
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Balanced and stable pressure in the circuit,
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6 minute defrost cycle, in accordance with manufacturer standards.
The client immediately felt an improvement in comfort and a reduction in perceived noise. The heat pump now operated smoothly and energy-efficiently, despite the -15°C outside temperature.
AirGreen Tips for Winter Maintenance of a Wall-Mounted Heat Pump
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Clear snow regularly around the outdoor unit to prevent ice buildup on the coil.
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Avoid covering the unit completely , even in winter — a rigid protective cap is sufficient.
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Schedule annual preventative maintenance before the cold weather sets in to check pressures and sensors.
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Monitor defrost cycles : if they become more frequent or longer, it's time to call a professional.
AirGreen: expertise, rigor and proximity
Our team of HVAC experts operates throughout Montreal , Laval , Longueuil , the North Shore and the South Shore , with repair, maintenance and installation services tailored to all brands — including Friedrich, Fujitsu, Midea, Sharp, Gree, and more.
Each intervention is an opportunity for us to demonstrate our know-how: diagnose precisely, intervene effectively and guarantee the long-term reliability of your HVAC system .