System Diagnosis
Air in System Symptoms
Air in system can be caused by low side leak or improper servicing. If low side leak occurs, temperature control will not achieve temperatures and compressor will run continuously. Compressor will eventually pump low side into a vacuum, drawing air and moisture into system. Air and R134a do not mix. Air pressure will be added to normal head pressure, resulting in higher than normal head pressures.
Determine if air is present by reading head pressure gauge with refrigerator off and evaporator and condenser at same temperature. Verify temperature on condenser outlet tube. Temperature should be within 3° or 4°F of what "Pressure and Temperature Relationship Chart" shows for a given idle head pressure. If temperature of condenser outlet is considerably lower than idle head pressure of gauge, air is in system.
Diagnose air in system by completing the following:
1.Thoroughly check for leaks.
2.Correct leak source. Do not attempt to purge air off. This could result in an undercharged system.
3.Discharge system.
4.Replace
5.Evacuate and recharge system with specified refrigerant charge.
Low or High Ambient Temperature Installation Symptoms
Lower ambient air temperature reduces condensing temperature and temperature of liquid entering evaporator. Increase in refrigeration due to operation in lower ambient results in decrease in power consumption and run time. At lower ambients there is reduction in cabinet heat leak which is partially responsible for lower power consumption and run time.
An increase in refrigeration will not occur below certain minimum ambient temperature. Temperature varies with type and design of refrigerator.
Ambient temperatures lower than 55°F will affect efficiency. The higher the ambient temperature, the higher the head pressure must be to raise the high side refrigerant temperature above condensing medium. Head pressure will be higher as ambient temperature raises. Refrigerators installed in ambient temperatures lower than 55°F will not perform effeciently because system pressures are generally reduced and unbalanced. Lower head pressure forces less liquid refrigerant through capillary line, resulting in symptoms of refrigerant shortage. The lower the ambient temperature, the more pronounced the condition.
When ambient temperature is below
Drain traps will freeze in ambient temperatures of 32°F.
Heat Load Symptoms
Increased heat load can result from addition of large supply of foods, excessive door openings, poor door sealing, interior light remaining on, etc.
Increased heat being absorbed by refrigerant in evaporator will affect temperature and pressure of gas returning to compressor. Refrigerator and freezer temperatures, power consumption, discharge, and suction pressures are all affected by heat load. Pressures will be higher than normal under heavy heat load.
RS1200001 | 12 | November 1996 |