Summer heat spikes head pressure across industrial refrigeration units. As ambient temperatures rise, condensing pressures climb alongside motor load. Performing preventative compressor maintenance ahead of the hot season keeps high-pressure cutouts and thermal overload from shutting down cold storage operations.
Hot ambient air directly cuts into condenser heat rejection. Fouled coils or failing fans rapidly push head pressures beyond design limits.
Coil Condition: Check air-cooled fin stock and evaporative condenser tube bundles for dirt or scale buildup. Any surface restriction chokes airflow, driving condensing temperatures past the standard 45°C to 50°C operating window. Wash coils using suitable non-corrosive cleaners.
Fans and Pumps: Measure current draw on condenser fan motors and check V-belt tension. On evaporative condensers, clear clogged nozzles to maintain uniform water flow over the tubes.
Extended high-load running thins out compressor oil and speeds up oxidation.
Oil Condition and Pressure: Inspect oil clarity through the sump sight glass. Darkened fluid signals thermal breakdown or acid accumulation. Verify net oil differential pressure—ensure it stays at or above 0.15 MPa (1.5 bar) during operation.
Crankcase Heaters: Check that crankcase heaters (typically 50W to 150W) power on automatically when the unit stops. Keeping oil temperature 20K above ambient prevents refrigerant from migrating into the crankcase during off-cycles.
Correct valve settings prevent liquid slugging while maintaining cooling capacity in the cold storage space.
Suction Superheat: Take pressure and temperature readings at the suction service valve. Maintain suction superheat between 5K and 10K. Running lower risks feeding liquid refrigerant into the compressor, while higher superheat pushes discharge temperatures past the 120°C safety limit.
Liquid Subcooling: Check liquid subcooling before the expansion valve. A range of 3K to 5K prevents liquid line flashing under heavy cooling loads.
Higher operating currents during summer worsen resistance at loose electrical joints.
Power Terminals: Lock out primary power and torque-check all terminal lugs inside the electrical box. Thermal expansion cycles loosen terminal screws over time.
Contactors: Inspect contactor points for pitting or heavy carbon deposits. Replace worn contactors to keep voltage unbalance between phases below 2%.
Completing these routine checks before summer peak loads ensures steady refrigeration performance and protects equipment life.
