Fluctuating Discharge Pressure


Probable Cause: Remedy:
Faulty condensing water regulating valve.
Insufficient charge- usually accompanied by corresponding fluctuation in suction pressure.
Cycling of evaporative condenser.
Replace condensing water regulating valve.
Add charge to the system.
Inadequate and fluctuating supply of cooling water to condenser. Check spray nozzles, coil surface, control circuits, thermostat overloads, etc.
Repair or replace any defective equipment.
Clean any clogged nozzles, coil surface, etc.
Check water regulating valve and repair or replace if defective.
Check water circuit for restrictions.
Determine causes of cycling fan and correct.
Adjust, repair or replace controls.
Cooling fan for condenser cycling.
Fluctuating discharge pressure controls on low ambient air-cooled condenser.
Fan cycling based on pressure switches.
Normal for fan cycling operation.
To eliminate, base fan cycling on ambient air temperature.
Use variable fan speeds or flooded type head pressure control system, but not both together.