An air conditioner that no longer cooled despite a normal display
At AirGreen , we were recently contacted by a customer in the Rosemont–La Petite-Patrie neighborhood of Montreal for a Sharp wall-mounted air conditioner repair . The customer, concerned that the unit was displaying a temperature of 16°C without generating any cold , feared a major failure of the compressor or the refrigeration circuit.
Our team came out the next day to perform a complete on-site diagnosis . The unit in question, a Sharp ZU1 series , is known for its reliability, but like any HVAC system, it can develop anomalies related to wear, lack of maintenance or electrical surges.
Initial diagnosis: a sensor and airflow problem
As soon as the front hood was removed, our technicians observed several revealing elements:
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The air filters were clogged with dust and pollen.
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The indoor temperature sensor (NTC) was detached from its housing , which distorted the ambient temperature reading.
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The unit was operating in ventilation mode only, without activation of the outdoor compressor.
After checking the control module, we confirmed that the cooling demand signal was not being transmitted to the outdoor unit due to this sensor error. The system believed it had already reached the target temperature.
AirGreen intervention: precision and technical rigor
Our technicians undertook a three-step repair :
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Correct reassembly and fixing of the NTC temperature probe , with replacement of the insulating support to ensure reliable reading.
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Thorough cleaning of air filters and evaporator using a certified HVAC disinfectant cleaner.
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Communication test between indoor and outdoor units to confirm resumption of the refrigeration cycle.
During performance tests, the air conditioner returned to optimal operation: the compressor started, the air flow increased and the air outlet temperature reached 9°C in less than 4 minutes .
Optimization and additional verification
To ensure a lasting repair, we also have:
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Checked the R410A refrigerant pressure , which was found to be correct.
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Cleaned the motorized shutter sensor , sometimes blocked by dust.
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Reset the Sharp control system , often useful after a replaced sensor.
After a 20-minute observation, the ambient temperatures stabilized at 22°C , without fluctuations or unexpected shutdowns. The customer immediately noticed the return of the comfort and quiet operation typical of Sharp units.
Maintenance and prevention tips
To prevent this type of breakdown from recurring, we provided the customer with our AirGreen maintenance recommendations :
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Clean the filters every four weeks during the summer.
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Schedule a complete annual maintenance (cleaning the evaporator and condenser, checking the sensors).
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Check the probe position after cleaning the front panel.
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Maintain a stable electrical voltage using a small regulator, ideal for older homes in Montreal.
These simple actions help extend the life of the system and ensure optimal energy efficiency .
AirGreen: your HVAC specialist in Montreal and the South Shore
This intervention in Rosemont illustrates AirGreen's philosophy : rigor, speed and transparency. Our RBQ and CCQ certified technicians work on all brands of wall-mounted air conditioners — Sharp, Fujitsu, Gree, Midea, Lennox, Bosch — throughout Greater Montreal , Laval , the North Shore and the South Shore .
Each service includes a complete diagnosis , a guaranteed repair , and personalized recommendations to avoid recurring breakdowns.
A quick repair, comfort restored
Thanks to a targeted sensor repair and a deep cleaning , the customer's Sharp wall-mounted air conditioner has regained its full performance. This type of problem, often perceived as major, is often due to a simple sensor or maintenance fault , which our team knows how to diagnose accurately.
AirGreen is the assurance of a reliable, professional and sustainable HVAC service, adapted to each home in Greater Montreal.