When a Direct Air heat pump refuses to start: an urgent call to Saint-Lambert
One particularly hot summer morning, a resident of Saint- Lambert , on Montreal's South Shore, contacted AirGreen after noticing that his Direct Air wall-mounted heat pump was no longer starting. The outdoor unit, installed on a metal bracket against the house's vinyl siding, appeared to be in perfect visual condition. However, despite the start command on the remote control, no compressor or fan sound could be heard.
This type of failure is common on older Direct Air models, where the outdoor control board can deteriorate after several seasons of freezing and thawing.
Accurate diagnosis: a communication failure between the units
Upon our arrival, our technicians undertook a series of systematic checks:
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Supply voltage : stable and compliant with 240 V.
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Indoor unit control signal : present.
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External module response : absent.
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Visual inspection of the wiring : no apparent damage, but slight oxidation at the terminals.
Upon opening the service panel, we detected an oxidized electronic board , particularly around the main relay. This type of corrosion often develops when the top cover is not perfectly sealed , allowing moisture to penetrate and creating an electrical leak path.
To confirm, we connected an AirGreen test module to simulate communication between the units: the heat pump responded immediately. The diagnosis was therefore confirmed: the outdoor control board was defective .
Repair: card replacement and full recommissioning
We replaced the main circuit board with a genuine Direct Air part, compatible with the 12,000 BTU model.
The repair included several key steps:
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Complete cleaning of the electrical compartment with compressed air.
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Applying an insulating varnish to the new board to prevent future corrosion.
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Tighten connections and test continuity on signal cables.
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Replacement of aging cable glands to ensure better sealing of the housing.
Once the system was reconnected, we performed a series of operational tests:
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The outside fan started instantly.
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The rotary compressor started with a stable current of 6.8 A, perfectly within the recommended range.
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After 10 minutes, the interior blowing temperature reached 10.5°C , proof of effective refrigeration.
Prevention: How to avoid this type of breakdown on Direct Air wall units
We advised the customer on several measures to extend the life of their system:
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Install a small protective canopy over the condenser to reduce exposure to rain and snow.
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Clean the unit every spring , especially the condenser fins, to prevent dust buildup.
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Have the electronic board inspected every 2 to 3 years , especially for models installed near a wall without sufficient rear ventilation.
Additionally, annual maintenance checks R-410A refrigerant pressure , discharge temperature, and fan condition—all parameters critical to the proper operation of the system.
A fast and durable repair from AirGreen
In less than two hours, the customer's Direct Air heat pump was fully operational again. This intervention perfectly illustrates the value of a professional diagnosis: what seemed like a major failure turned out to be a simple faulty electronic board , repaired on site thanks to our mobile parts inventory.
At AirGreen , we ensure that every service call results in a complete restoration of indoor comfort , while clearly explaining the causes and preventative measures.
Our teams operate every day in Montreal, Laval, Longueuil, on the North Shore and the South Shore , offering reliable and transparent HVAC service, regardless of the brand of your device — Direct Air, Gree, Fujitsu, Midea, Sharp, Zephyr or Lennox .