Refrigeration System Troubleshooting usingSystemPressureandSuperheatMeasurements HEAD SUCTION HIGH HIGH LOW POSSIBLE PRESSURE PRESSURE SUPERHEAT CAUSE

Insufficient airflow across condenser

CORRECTION Check for dirty or damaged condenser coil

Check condenser fan operation

HIGH HIGH HIGH

System overcharged System overloaded

Evacuate and recharge

Check for proper equipment load sizing

Check for excessive humidity*

HIGH HIGH

HIGH LOW

VARYING LOW

Air in system

Insufficient airflow across evaporator

Evacuate and recharge

Check for dirty or clogged air filter

Check evaporator blower operation

Check for blocked or inadequate return air

Check for improperly sized duct system

HIGH LOW LOW LOW HIGH HIGH Restriction in liquid line System undercharged Restriction in suction line LOW HIGH LOW Overfeeding metering device

Locate and remove, evacuate and recharge

Evacuate and recharge

Locate and remove, evacuate and recharge

Check for moisture in system

Replace expansion valve LOW

LOW LOW

LOW LOW

LOW VARYING HIGH

System underloaded Incorrect refrigerant VARYING Faulty compressor valves

Check for proper equipment load sizing

Evacuate and recharge Replace compressor

* Effective system cooling capacity is reduced approximately 1000 BTUH per pint of humidity removal.