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TROUBLE DIAGNOSES FOR ABNORMAL PRESSURE Whenever abnormal pressure of high and/or low sides of the system is noted, diagnosis must be conducted Gauge indication Refrigerant cycle Probable cause Corrective action Both high- and low-pressure AC359A I Pressure is reduced soon Excessive refrigerant charge in Reduce refrigerant until speci- Air suction by radiator or con- Insufficient condenser cooling " q 1 Condenser fins are clogged. q 2 Improper rotation of radiator fan or condenser fan I Clean condenser. I Check and repair radiator or I Low-pressure pipe is not I When compressor is stopped 2 , 28 psi). It then decreases gradually Poor heat exchange in con- " Air in refrigeration cycle Evacuate repeatedly and Engine tends to overheat. Engine cooling systems mal- Check and repair each engine I Areas near low-pressure I Plates are sometimes cov- I Excessive liquid refrigerant I Excessive refrigerant dis- I Expansion valve is open a " q 1 Improper thermal valve installation q 2 Improper expansion valve adjustment Replace expansion valve. DIAGNOSES — Overall System Performance Test Diagnoses (Cont’d) HA-32 |