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Réparation d’une thermopompe murale LG à Rosemont–La Petite-Patrie
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Repair of an LG wall-mounted heat pump in Rosemont–La Petite-Patrie

An AirGreen service call in a brick duplex in Montreal

In the residential neighborhood of Rosemont–La Petite-Patrie , our technicians were recently called to work on an LG wall-mounted heat pump installed on the rear facade of a brick duplex. The customer had been reporting a noticeable loss of heat for several days, despite a normal display on the remote control. The outdoor unit, visible on the building's wall, appeared to be operating intermittently, a typical symptom of a communication problem or a faulty compressor .

Initial diagnosis: analyze before acting

Upon arrival on site, our AirGreen technician carried out a complete inspection of the HVAC system . Several elements were quickly observed:

  1. The LG outdoor compressor would start in 30-40 second bursts before abruptly stopping.

  2. No error code visible on the indoor unit — a clue pointing to an external electronic board .

  3. The indoor blowing temperature remained stable around 22°C, without fluctuation, confirming the absence of active heating.

  4. The compressor amperage measured with the multimeter showed irregular consumption , characteristic of an aborted engine start .

Step 1: Checking the electronic card

LG systems are renowned for their reliability, but like any electronic device, the control board can be damaged by moisture or electrical fluctuations.
Our technician removed the rear condenser protection plate and found traces of oxidation on the power module (PCB).

Solution implemented:

  • Cleaning the board using a specialized dielectric solvent.

  • Complete drying under compressed air.

  • Continuity and resistance test on main relays.

  • Application of a protective varnish to prevent any further moisture infiltration.

Step 2: Test the compressor and electrical connections

Once the board was reinstalled, the LG R1 rotary compressor was manually tested via a controlled start-up. The voltage and current values ​​returned to normal.
The technician also tightened the connections on the terminal block and replaced a slightly oxidized cable connecting the indoor unit to the outdoor unit.

Step 3: Check the refrigeration cycle

After a complete system reboot, the following measurements were taken:

  • Suction pressure: stable at 120 psi.

  • Discharge pressure: around 350 psi — normal values ​​for an LG R-410A heat pump.

  • Indoor blowing temperature: 31.2°C after 5 minutes, confirming the return of heating.

Cleaning and preventive maintenance

To ensure the longevity of the system, a thorough cleaning of the outdoor coil was performed. The accumulation of dust and spring pollen was hampering heat transfer.
Additionally, we advised the customer to have their system checked once a year , before the heating season, to prevent moisture from damaging the control board again.

Result: comfort restored and efficiency regained

At the end of the intervention, the LG heat pump was working perfectly. The customer immediately noticed a rapid rise in the indoor temperature , and the compressor noise had stabilized, a sign of a balanced operating cycle .
Thanks to targeted repair and comprehensive maintenance, the device was restored to its original performance without costly replacement.

AirGreen expertise serving Montrealers

This type of intervention perfectly illustrates AirGreen's philosophy : to diagnose accurately, repair intelligently and maximize the durability of existing equipment.
Our certified technicians work every day on wall-mounted HVAC systems throughout the region— Montreal, Laval, Longueuil, the North Shore, and the South Shore —adapting to the specific features of each building, whether it's a century-old duplex, a modern condo, or a single-family home.

Some AirGreen maintenance tips

To extend the life of your LG wall-mounted heat pump :

  • Clean the internal filters regularly (every 4 weeks during use).

  • Make sure the outdoor unit is clear of any obstructions (plants, snow, leaves).

  • Have your refrigerant pressure checked every two years by a certified technician.

  • Use a surge protector to protect the circuit board from overvoltages.

With these best practices, your HVAC system will remain efficient, economical and reliable throughout the year.