Refrigeration System Section 77-4 Part No. 80-1214-3Refrigeration System DiagnosticsGeneralWhen analyzing the refrigeration system, it is important tounderstand that different refrigeration componentmalfunctions may cause very similar symptoms.Many external factors can make good refrigerationcomponents appear bad. These factors can includeimproper installation, or water system malfunctions suchas hot incoming water supply or water loss.The following two examples illustrate how similarsymptoms can result in a misdiagnosis.1. An expansion valve bulb that is not securelyfastened to the suction line and/or not insulated willcause a good expansion valve to flood. If a servicetechnician fails to check for proper expansion valvebulb mounting, he may replace the expansion valvein error.The ice machine now functions normally. Thetechnician erroneously thinks that the problem wasproperly diagnosed and corrected by replacing theexpansion valve. Actually, the problem (loose bulb)was corrected when the technician properlymounted the bulb of the replacement expansionvalve.The service technician's failure to check theexpansion valve bulb for proper mounting (anexternal check) resulted in a misdiagnosis and theneedless replacement of a good expansion valve.2. An ice machine that is low on refrigerant may causea good expansion valve to starve. If a servicetechnician fails to verify the system charge, he mayreplace the expansion valve in error.During the replacement procedure, recovery,evacuation and recharging are performed correctly.The ice machine now functions normally. Thetechnician erroneously thinks that the problem wasproperly diagnosed and corrected by replacing theexpansion valve.The service technician's failure to check the icemachine for a low refrigerant condition resulted in amisdiagnosis and the needless replacement of agood expansion valve.Revised 8/2003Downloaded from www.Manualslib.com manuals search engine
