Case 580SR Service Manual page 791

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PERFORMANCE TEST DIAGNOSIS CHART
Pressure gauge values: Low pressure - High
Evaporator air not cold
PERFORMANCE TEST DIAGNOSIS CHART
Pressure gauge values: Low pressure - Normal
Insufficient cooling
Low pressure reading does
not fluctuate with changes in
temperature control switch
(pressure should lower until
compressor cycles)
Evaporator air not cold
PERFORMANCE TEST DIAGNOSIS CHART
Pressure gauge values: Low pressure - High
Compressor cycles ON and
OFF too frequently
SECTION 50 - CAB HEATING AND AIR CONDITIONING
High Pressure - Low
PROBLEM
Internal leak in compressor (reed
valves, gasket, worn or scored pis-
ton rings or cylinder)
High Pressure - Normal
PROBLEM
System low on charge. Air or mois-
ture present in system
High Pressure - Normal
PROBLEM
Defective temperature control (ther-
mostatic) switch
POSSIBLE CAUSE
POSSIBLE CAUSE
POSSIBLE CAUSE
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CORRECTION
Discharge the system.
Replace the compressor.
Evacuate the system.
Charge the system.
Re-test.
CORRECTION
Perform leak test.
Discharge the system.
Repair leaks.
Replace receiver/drier.
Check oil level.
Evacuate the system.
Charge the system.
Re-test.
CORRECTION
Stop engine and shut off A/C.
Replace temperature control switch.
Re-test system and check compres-
sor cycling.
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