l  The  magnetic  valves  that  control  the  flow  of DETECTING AND CORRECTING refrigerant PROBLEMS l  The  wiring  system  that  connects  the  sensing A  number  of  symptoms  indicate  faulty  operation  of elements to the solenoids of the magnetic valves refrigeration  and  air-conditioning  plants.  Figures  5-7, and the controller of the electric heaters 5-8,  and  5-9  list  some  of  the  problems  along  with Trouble High condensing pressure. Possible Cause Corrective Measure Air on noncondensable gas in system. Purge air from condenser Inlet water warm. Increase  quantity  of  condensing  water. Insufficient water flowing through Increase quantity of water. condenser. Condenser tubes clogged or scaled. Too much liquid in receiver, condenser tubes submerged in liquid refrigerant. Clean condenser water tubes. Draw  off  liquid  into  service  cylinder. Low condensing pressure. Too much water flowing through condenser. Reduce quantity of water. High  suction  pressure. Water too cold. Reduce  quantity  of  water. Liquid refrigerant flooding back from Change expansion valve adjustment, evaporator. examine fastening of thermal bulb. Leaky discharge valve. Remove head, examine valves. Replace any found defective. Overfeeding of expansion valve. Regulate expansion valve, check bulb attachment. Low  suction  pressure. Leaky suction valve. Restricted  liquid  line  and  expansion valve or suction screens. Insufficient refrigerant in system. Too  much  oil  circulating  in  system. Remove head, examine valve and replace if worn. Rump down, remove, examine and clean screens, Check for refrigerant storage. Check for too much oil in circulation. Remove  oil. Improper adjustment of expansion valves. Adjust valve to give more flow. Expansion valve power element dead Replace expansion valve power or  weak element. Figure  5-7.—Trouble  diagnosis  chart. 5-13