An air conditioner open during diagnosis
At AirGreen , we often see wall-mounted air conditioning units with the front panel removed before our arrival, a sign that the customer tried to figure out the problem on their own. This is exactly what we saw in Saint-Lambert , on Montreal's South Shore , where a Fujitsu wall-mounted air conditioner refused to blow cold air in early spring.
The owner, concerned about the approach of warm weather, contacted us after noticing that the indoor fan was running intermittently and that the unit was sometimes giving off a burning smell . Upon observing the open unit, we immediately recognized an electrical connection problem and a buildup of dirt on the evaporator coil .
Detailed diagnosis: the importance of electrical safety
From the first inspection, our technicians identified several problematic elements:
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Partially exposed electrical wires near the main terminal block.
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Traces of overheating on the control board connector.
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Evaporator coil clogged with dust and nicotine, reducing heat exchange.
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Clogged and deformed filters , probably not replaced for several seasons.
The whole thing explained not only the lack of performance, but also the risk of an electric arc that could lead to shutdowns or complete malfunction of the fan.
Fujitsu Air Conditioner Repair Steps
1. Power cut and secure inspection
Before any work was done, we disconnected the system's circuit breaker to ensure safety. An ohmmeter check confirmed that the control wires were not deeply damaged.
2. Connector replacement and complete cleaning
The burnt connector was replaced with a new insulated terminal block , and the wires were then repositioned according to the original Fujitsu diagram. We then cleaned the evaporator coil using a biodegradable foaming product , before rinsing with a pressure extractor designed for wall-mounted systems.
The drain pipe was also cleared to avoid any risk of subsequent leakage onto the wall or floor.
3. Blower Motor Overhaul
The indoor fan motor was disassembled and dusted. After testing, a slight persistent noise indicated rotor misalignment . A recalibration was performed and the bearing received a light application of dielectric lubricant to extend its life.
4. Checking the refrigerant circuit
The outdoor condenser, accessible from the rear of the residence, was reading slightly lower than normal . We performed a measured top-up of R-410A refrigerant and checked the flare connection for leaks. No signs of leaks were detected.
Result: performance and safety restored
Once the system was closed and restarted, the difference was immediate. The Fujitsu wall unit was now blowing air at 9°C , compared to 18°C before our intervention. The fan was running stably, and any burning smell was gone .
The customer expressed relief, pleased to see that the repair had avoided a complete replacement of his unit. We recommended annual maintenance to prevent the reappearance of deposits on the coil and maintain consistent performance throughout the summer.
AirGreen Tips: Never Ignore an Electrical Sign
A wall-mounted air conditioner that emits an unusual odor or whose front panel heats up slightly may be hiding a serious electrical problem . At AirGreen, we recommend:
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Immediately turn off the power if you smell burning plastic.
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Never handle internal connections without insulated tools and without disconnecting the circuit breaker.
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To plan an annual professional maintenance including checking the electronic card and terminal block.
Simple preventative maintenance costs much less than replacing a motor or control board.
AirGreen: your HVAC expert in Montreal, Laval and the South Shore
Every service call is an opportunity for us to demonstrate our expertise and rigor. Our certified technicians work on all major brands— Fujitsu, Gree, Sharp, Hitachi, Midea, Goodman —and ensure fast, reliable repairs that meet the strictest HVAC standards.
Whether in Saint-Lambert , Longueuil , Montreal , Laval or elsewhere in the metropolitan area, AirGreen guarantees professional and transparent service , always focused on the performance and security of your system.