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Unit Short Cycles

QuestionsCauseRemedy
What is the thermostat differential setting?Control differential set too closelyWiden differential
Have you checked condenser?Cycling on high pressureClean dirty condenser. Check water supply on water-cooled condenser
Have you checked Discharge valve?Discharge valve leakinCorrect condition
Have you checked the sight glass?Shortage of refrigerantReclaim overcharge
 Refrigerant overchargeReclaim overcharge
Have you checked the expansion valve?Leaky expansion valve.Replace
Is compressor hot?Compressor-motor overload cutting outCheck for high head pressure, tight bearings, stuck pistons, clogged air or water-cooled condenser or water shut-off

 

Unit Operates Long or Continuously

QuestionsCauseRemedy
How long do the doors stay open?Service load to highKeep doors closed
Is the condenser clean?Dirty condenserClean condenser
Are the condenser fans running?Fans not runningRepair or replace
Is the evaporator dirty or iced up?Iced or plugged evaporator coilDefrost or clean
Are the evaporator fans running?Fans not runningRepair or replace
Have you checked the refrigerant level?Shortage of refrigerantRepair leak and recharge
Is there air or other non-condensables in the system?Non-condensables in the systemRemove from the system
Are all controls functioning properly?Control contacts have frozenClean points or replace control
Have you checked expansion valve?Plugged expansion valve or retainerClean or replace
What is Evaporator Superheat?Evaporator Superheat too highAdjust expansion valve to lower Superheat setting
Where is condensing unit located?Location too warmVentilate area or change to cooler location
Is box well sealed from air penetrations?Wall panels not locked or wall penetrations not sealedLock panels, seal penetrations or replace
Is system capacity sufficient for product load?Product load greater than system capacityAdd additional units or replace

 

Noisy Unit

QuestionsCauseRemedy
Have you checked oil charge?Insufficient compressor oilAdd oil to proper level
Are all refrigerant lines secured so that no rattling occurs?Tubing rattleBend tubes away from other metal contacts
Are all mountings tight?Mountings looseTighten
Is the noise coming from the compressor? Do you have LOW suction superheat? (Below 20¡)Oil slugging or refrigerant flooding backAdjust oil level or refrigerant charge. Check expansion valve for leak or oversize orifice