Findings: Condensing pressure too high

Cause: Air or other non-condensable gases in refrigerant system.

 Action: Purge the condenser by using reclaim system, start and run system until it reaches running temperature. Purge again if necessary.

Cause: Condenser surface too small.

  Action: Replace condenser with larger size.

Cause: Refrigerant system charge too large (liquid collection in condenser).

 Action: Recover refrigerant until condensing pressure is normal. The sight glass must remain full.

Cause: Condensing pressure regulation set for too high a pressure.

Action: Set for the correct pressure. 

Cause: Dirt on condenser surface. (AC)

Action: Clean condenser 

Cause: Fan motor or blade defective or too small.

 Action: Replace motor or fan blade or both

Cause: Air flow to condenser restricted.

 Action: Remove air inlet obstruction or move condenser.

Cause: Incorrect air flow direction through condenser.

 Action: Change rotation of fan motor. On condensing units, air must flow through condenser and then to compressor.

Cause: KVR condensing pressure regulator set too high.

 Action: Change rotation of fan motor. On condensing units, air must flow through condenser and then to compressor.

Cause: Ambient temperature too high.

 Action: Create fresh air inlet or move condenser.

Cause: Short-circuit between condenser fan airside pressure and suction sides.

Action: Install a suitable duct, possibly to outdoor air. 

Cause: Bellows in KVR condensing pressure regulator might be leaking.

Action: Slowly loosen protective cap. If pressure or traces of refrigerant exist under the cap, there is a leak in the bellows. Replace valve.

Findings: Condensing pressure too low

Cause: Condenser surface too large.

 Action: Establish condensing pressure regulation or replace condenser with a smaller one.

Cause: Low load on evaporator.

 Action: Establish condensing pressure regulation.

Cause: Suction pressure too low, e.g. insufficient liquid in evaporator.

 Action: Locate fault on line between condenser and thermostatic expansion valve.

Cause: Compressor suction and discharge valves might be leaking.

 Action: Replace compressor valve plate (semi-hermetic compressor) or replace compressor (hermetic compressor)

Cause: Condensing pressure regulator set too low.

 Action: Set condensing pressure regulator to correct pressure.

Cause: Un-insulated receiver placed too cold in relation to condenser (receiver acts as condenser).

 Action: Move receiver or fit it with suitable insulating cover.

Cause: Air temperature too low. (AC)

 Action: Establish condensing pressure regulation.

Cause: Air volume through condenser too large. (AC)

 Action: Replace fan with smaller unit or establish motor speed regulation.

Cause: Water flow rate too high. (WC)

 Action: Install WVFX automatic water valve or set existing valve correctly

Cause: Water temperature too low. (WC)

 Action: Decrease water volume / flow by using a WVFX automatic water valve, for example

Cause: Water quantity too large. (WC)

 Action: Set WV water valve for smaller water quantity, i.e. higher pressure.

Cause: WV water valve open because of defective lower diaphragm. (WC)

 Action: Check water valve for cracks in diaphragm. Replace diaphragm. See spare parts catalogue*. There must be no pressure on bellows element during removal and refitting.

Cause: WV water valve cannot close because of dirt in the seat. Valve cone sticks because of dirt. (WC)

Action: Check water valve for dirt and clean it. Replace parts as necessary. See spare parts catalogue. There must be no pressure on bellows element during removal and refitting. Install a filter ahead of the water valve." 

Findings: Condensing pressure erratic

Cause: Differential on start/stop pressure control for condenser fan too large. Can cause vapour formation in liquid line for some time after start of condenser fan because of refrigerant collection in condenser.

 Action: Set differential on lower value or use valve regulation (KVD + KVR) or use fan motor speed regulation.

Cause: Thermostatic expansion valve hunting.

 Action: Set thermostatic expansion valve for higher superheat or replace orifice with smaller size

Cause: Fault in KVR/KVD condensing pressure regulating valves (orifice too large).

 Action: Replace valves with smaller size.

Cause: Consequence of hunting suction pressure.  

 Action: See "Suction pressure hunts".

Cause: Wrong sized or located check valve in condenser line.

 Action: Check sizing. Mount check valve below condenser and close to receiver inlet.

Cause: WV water valve too large.(WC)

 Action: Replace water valve with a smaller size.