High-rise intervention in a downtown condo
One Tuesday morning, our AirGreen team was contacted by a client residing in a condo in downtown Montreal , specifically in the Ville-Marie district. The client reported a complete failure of their Zephyr PTAC (Packaged Terminal Air Conditioner) system , a unit installed under the large living room window overlooking a balcony. This type of unit, often found in multi-unit buildings or condos, provides both heating and cooling from a single compact module passing through the exterior wall.
The customer had noticed that the system had not been heating for several days , despite a normal display on the control panel. With the May weather still cool, this situation quickly became uncomfortable.
Initial diagnosis: an internal electrical fault
Upon arrival, our technicians immediately performed a complete visual diagnostic of the unit. The Zephyr unit was clean and well-maintained, but the exhaust grille showed signs of moisture. Upon inspection, the heating circuit's thermal fuse was blown. This essential component acts as a protection against electrical overloads and overheating—its failure prevents the heating mode from being activated.
We then removed the top cover to access the electrical resistance module . Using a digital multimeter , we confirmed that the resistance itself was intact, but that the high-limit safety thermostat was no longer closing the circuit, even at room temperature.
Steps of repair
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General power cut to ensure safe intervention.
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Replacement of the thermal fuse and safety thermostat with genuine Zephyr parts, CSA certified.
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Cleaning the evaporator and condenser coils , which are clogged with dust and textile residue — a common cause of overheating.
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Cross fan lubrication , to reduce noise and improve airflow.
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Complete heating and cooling mode test , confirming full functionality of the system.
After powering up, the unit restarted instantly. The hot airflow was steady and consistent, and the operating noise was almost imperceptible—proof that the repair had been carried out according to AirGreen standards.
A typical PTAC environment: challenges and precautions
PTAC systems , often used in condos, hotels, and buildings with floor-to-ceiling windows, pose unique challenges. They are directly exposed to the outdoors, increasing the risk of corrosion and blockage of the condensate drain . In this case, the presence of shoes placed on the grille also contributed to limiting airflow , causing the internal module to overheat.
Our technicians therefore took the time to explain some good maintenance practices to the customer:
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Never obstruct the PTAC ventilation grilles .
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Clean the filters every two months with a low-power vacuum cleaner.
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Check that condensate drains properly each season.
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Schedule annual AirGreen maintenance to ensure system longevity.
Energy efficiency at the heart of the intervention
This type of Zephyr system is designed to provide individual heating and cooling solutions for each residential unit. However, over time, performance issues can occur if the control module or temperature sensor becomes out of sync. Our technicians also recalibrated the wall thermostat, allowing the customer to reduce their electricity consumption while maintaining consistent comfort.
In addition, we recommended that the client consider, in the medium term, replacing the unit with a PTAC Zephyr model using R-32 refrigerant , which is more environmentally friendly and energy efficient. This type of upgrade is eligible for certain local subsidies , particularly in the Montreal region and on the South Shore, when it comes to energy modernization.
Result: restored comfort and successful prevention
After final testing, the Zephyr system was back up and running at 100%. The relieved customer was able to enjoy stable thermal comfort while admiring the city view from his balcony.
At AirGreen , we know that a simple PTAC can become a crucial link in urban residential comfort. Thanks to our expertise in HVAC system repair and maintenance , we guarantee each client transparent, sustainable and professional service — whether in Montreal, Laval, on the North Shore or the South Shore .