Urgent call for air conditioner frozen by ice
At AirGreen , we recently received an emergency call from a homeowner in Sainte-Thérèse , on the North Shore of Montreal. Their Fujitsu wall-mounted air conditioner was no longer blowing cool air, and an unusual noise was being heard inside. After opening the front panel, our client discovered a worrying phenomenon: the coils of the indoor unit were completely frozen .
This type of problem is common at the beginning of the warm season, especially when the device has not been serviced for several months.
On-site diagnosis: lack of maintenance combined with air restriction
Upon our arrival, our technician identified two main causes:
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Clogged air filters preventing sufficient air circulation.
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Too low an evaporator temperature , causing ice to form on the fins.
After removing the filters, it was evident that accumulated dust was preventing air from circulating freely. This lack of airflow often causes a pressure imbalance in the refrigeration circuit, leading to gradual freezing of the evaporator.
Steps to Repair and Refurbish Air Conditioner
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Complete shutdown of the system for natural and safe defrosting.
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Thorough cleaning of filters and evaporator with a biodegradable solution.
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Check airflow and indoor fan to ensure proper operation.
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R-32 refrigerant pressure measurement , confirming a slight deficit. A controlled recharge was therefore carried out.
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Performance test after restart: air outlet temperature measured at 9°C, confirming a return to optimal performance.
This was completed with antibacterial disinfection , essential to prevent the proliferation of mold often caused by stagnant humidity after a frost.
Understanding the Causes of Frost on a Wall-Mounted Air Conditioner
Ice formation inside a wall unit can result from several factors:
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Clogged filters (like here).
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Refrigerant level too low.
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Defective temperature sensors.
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Interior fan slowed down.
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Room temperature too low when using air conditioning mode.
At AirGreen, we find that 80% of frosting cases on wall-mounted air conditioners are simply due to a lack of maintenance.
AirGreen tips to avoid another frost episode
To prevent this type of breakdown from recurring, we recommend to all our customers:
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Clean the filters every two months, especially during periods of heavy use.
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Schedule annual preventative maintenance , ideally in the spring, before the hot season.
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Avoid setting the thermostat too low (not below 20°C in air conditioning mode).
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Make sure nothing is blocking the air outlet (curtains, furniture, etc.).
These simple actions not only prevent frost, but also reduce energy consumption and extend the life of the system.
AirGreen expertise: speed, rigor and transparency
Our technician took the time to explain to the customer how his unit works, the warning signs of frost, and the importance of regular preventative maintenance . The Fujitsu air conditioner is now operating at full capacity, and the customer immediately felt comfort restored to his living room .
At AirGreen , we pride ourselves on providing professional and personal service, backed by over ten years of experience in HVAC system repair in Montreal, Laval, Longueuil, the North Shore, and the South Shore . Whether it's an electrical, refrigerant, or performance issue, our teams respond quickly and efficiently.
In conclusion
This intervention in Sainte-Thérèse demonstrates once again that regular maintenance can prevent costly repairs. Thanks to our precise diagnosis and careful intervention, our client's Fujitsu wall-mounted air conditioner is back to full efficiency—ready to ensure a comfortable and worry-free summer.