A compressor stopped on a roof during a heatwave
Montreal's flat roofs can sometimes put a strain on surface-mounted HVAC systems . During a service call in Côte-des-Neiges , our AirGreen team was called urgently to diagnose a Zephyr wall-mounted heat pump that had completely shut down in the middle of a summer afternoon. The client, a residential building owner, was concerned about the total lack of air conditioning for his tenants.
The compressor, located on the roof, no longer started despite repeated attempts to restart it.
Diagnosis: Start relay failure and compressor overheating
Upon our arrival, our technicians carried out a complete analysis of the control circuit .
The Zephyr condenser, exposed to the sun and resting on wooden blocks, showed several telltale signs:
-
Wiring insulation damaged by UV rays;
-
Traces of overheating on the connection box;
-
Lack of effective grounding ;
-
And above all, a melted start relay , preventing power to the compressor.
Using a digital multimeter confirmed that the compressor was not faulty: the resistance between windings was normal. The problem was therefore with the starter board and the relay .
This typical failure often occurs during high temperatures, when the case temperature exceeds 60°C , which accelerates the aging of electrical components.
Intervention: replacement of electrical components and upgrading of wiring
Our AirGreen team undertook a complete re-compliance of the electrical section of the Zephyr condenser:
-
Replacement of the starter relay with an original Zephyr model, CSA certified.
-
Installed a new 45+5 µF starting capacitor to stabilize the inrush current.
-
Restoration of the insulation sheath of cables exposed to UV with heat shrink sleeves.
-
Added full grounding to the condenser chassis.
-
Compressor test under load after restart.
Once the unit was restarted, the pressures and temperatures were checked:
-
Suction pressure: 120 psi
-
Discharge pressure: 365 psi
-
Indoor blown air temperature: 9°C
Everything indicated a return to optimal performance.
Result: restored air conditioning and increased security
Within minutes of the repair, fresh air was circulating through the building's living quarters again.
The Zephyr compressor ran quietly and smoothly, proving that the new relay and capacitor ensured smooth startup.
We completed the intervention by securely fixing the condenser on new anti-vibration supports , in order to avoid any accumulation of water or transfer of heat to the roof.
Prevention: AirGreen tips for rooftop installations
Rooftop heat pump installations require special attention. Here are AirGreen's key recommendations to extend the life of your Zephyr unit:
-
Check the condition of the wiring and insulation every two years;
-
Install UV protection on exposed ducts;
-
Ensure sufficient ventilation around the compressor (at least 60 cm clearance);
-
Clean the fins and check the units are securely fastened to avoid excessive vibration.
With these simple actions, power outages can be avoided and energy efficiency maintained throughout the summer season.
AirGreen: Zephyr experts in Montreal and the South Shore
At AirGreen , we are proud to be recognized as specialists in Zephyr system repair in Greater Montreal, whether in Côte-des-Neiges, Outremont, Ville-Marie, Brossard or Longueuil .
Our certified technicians respond to all types of breakdowns:
-
Electrical (board, relays, fuses, capacitor) ;
-
Refrigeration (leak, compressor, pressure switch) ;
-
Mechanical (fan, vibration, abnormal noise) .
Each intervention complies with the manufacturer's standards and guarantees safe and long-lasting operation .
In summary
-
Unit Type : Zephyr Wall-Mounted Heat Pump
-
Location : Côte-des-Neiges (Montreal)
-
Problem : Burnt out start relay, compressor inactive
-
Solution : Replaced relay and capacitor, revised wiring
-
Result : System restored, air conditioning reactivated, increased security
At AirGreen , we ensure the comfort of our customers, even on the most exposed roofs in Montreal.