Repair of a Yonan wall-mounted air conditioner in Saint-Bruno

A service call in the middle of winter for a reversible air conditioner

At AirGreen , we work year-round to ensure the proper functioning of residential HVAC systems, whether used for heating or cooling. This service call in Saint-Bruno , on Montreal's South Shore , involved a Yonan wall-mounted air conditioner installed in a modern living room, combining wood paneling and recessed lighting.

The customer contacted us after noticing that his wall unit was blowing lukewarm air, but was unable to heat the room, despite being set to heating mode. This type of symptom is common on reversible wall units , often caused by a four-way valve problem , a faulty sensor or a refrigerant leak .

Technical inspection and complete diagnosis

Upon our arrival, our RBQ certified technician performed a thorough inspection of the unit:

• Checking the operating mode : the compressor started, but the gas temperature at the condenser outlet remained low.

• Thermodynamic cycle analysis : the reversing valve did not switch completely, partially blocking the flow of refrigerant.

• Pressure check : suction pressure slightly lower than normal, suggesting a slow leak.

• Visual and electronic inspection : no error on the control board, but the four-way valve coil showed abnormal resistance.

The final diagnosis: faulty reversing valve (four-way) , accompanied by a micro-leak of refrigerant at the flare connection.

Complete repair of the Yonan wall-mounted heat pump

The intervention took place in several stages:

1. Recovery of remaining refrigerant to meet environmental standards (R-410A).

2. Replacement of the Yonan four-way valve with an equivalent original model.

3. Re-brazing and tightening of flare connections with the addition of specialized sealing paste.

4. Nitrogen leak test to confirm repair.

5. Complete vacuum draw of the circuit for 30 minutes.

6. Recharge with refrigerant according to the nominal capacity of the unit.

Once the system was closed and restarted, the technician checked:

• stable heating return with a hot air flow at 45°C at the outlet;

• the balanced pressure of the circuit;

• automatic operation of the defrost mode .

The Yonan wall-mounted air conditioner has resumed its optimal operation, providing immediate comfort to the customer.

Result: efficiency restored and comfort restored

Thanks to this repair, the system regained:

• maximum thermal performance , without fluctuation;

• energy efficiency in accordance with manufacturer parameters;

• increased reliability to face the winter.

Our interventions guarantee not only immediate repair, but also the prevention of future breakdowns thanks to a complete check of each component.

AirGreen Recommendations for Preventive Maintenance

In order to avoid this type of breakdown recurring, we recommended that the customer proceed to:

• a complete maintenance before each heating season ;

• cleaning the filters and the indoor coil every three months;

• an annual check of the refrigerant gas and connections .

These simple measures extend the life of the system and maintain optimal energy efficiency.

AirGreen: HVAC expertise serving South Shore homes

Every service call is an opportunity for us to demonstrate our technical rigor and our commitment to customer satisfaction .
Whether it's for a heat pump , a wall-mounted air conditioner or a multi-zone system , our technicians cover all of Greater Montreal , including Saint-Bruno, Longueuil, Brossard, Laval, the North Shore and the South Shore .

Thanks to our know-how and our methodical approach, we ensure lasting repairs that meet the highest standards of residential refrigeration .