Why Does an Air-Cooled Chiller Trigger a High-Pressure Alarm?

During hot summer months, many air-cooled chillers trigger high-pressure alarms, particularly in regions with extremely high ambient temperatures—often exceeding 45 °C—such as chillers in Saudi Arabia, the United Arab Emirates and Iraq.

Standard air-cooled chillers are equipped with comprehensive protective systems. When a high-pressure condition occurs, the protection mechanism is automatically activated, and the corresponding fault indicator light illuminates.

The primary cause of a high-pressure alarm is insufficient heat dissipation from the condenser. If this issue remains unresolved and the chiller continues to operate under high pressure for an extended period, it may lead to excessive current draw and ultimately result in compressor failure.

1. Air-cooled chillers rely on fans for condenser heat dissipation. When the ambient temperature exceeds 42 °C, the cooling efficiency decreases significantly, preventing effective removal of heat generated during refrigerant circulation.
2. Dirt accumulation or blockage on the condenser surface can severely impair heat transfer, leading to elevated pressure levels.

1. Inspect fan operation to ensure proper functionality.
2. Ensure adequate ventilation around the unit to allow efficient discharge of hot air.
3. In environments above 42 °C, consider auxiliary cooling methods such as external fans or shading structures to reduce surrounding temperatures.
4. Regularly clean the air filters and condenser fins using compressed air or appropriate cleaning tools.
5. For ambient temperatures near 42 °C, increase the condenser size by approximately 25%—a common practice for chillers using refrigerants such as R22, R407C, and R410A. For ambient temperature exceeding 45 °C, we recommend designing the system with R134a refrigerant, which supports operation at up to 55 °C. However, note that R134a has lower refrigeration efficiency, requiring a larger compressor to achieve equivalent cooling capacity, which increases overall system cost.

Note: Proper installation location is critical—air-cooled chillers should be installed in well-ventilated areas to ensure optimal airflow and long-term reliability.