Fujitsu FO20R Series Installation Instructions Manual page 72

9.0 DIAGNOSTICS & TROUBLESHOOTING
9.13 Troubleshooting Tips
SYSTEM
PROBLEM
Overcharge
Undercharge
Liquid Restriction
(Filter Drier)
Dirty Outdoor Coil
Low Outdoor
Ambient Temperature
Compressor
Bad Indoor Suction
Pressure Transducer or
Faulty Measurement
Poorly Insulated
Indoor Vapor Line
Thermistor or Bad
Thermistor
SYSTEM
PROBLEM
Overcharge
Undercharge
Liquid Restriction
(Filter Drier)
Dirty Indoor Coil
Low Indoor Ambient
Temperature
Compressor
Bad Outdoor Suction
Pressure Transducer or
Faulty Measurement
Poorly Insulated
Outdoor Vapor Line
Thermistor or Bad
Thermistor
72
COOLING MODE
TROUBLESHOOTING TIPS
DISCHARGE SUCTION
PRESSURE PRESSURE
High High
Low Low
Low Low
Low Low
High High
Low Low
Low High
Low Low
High High
HEATING MODE
TROUBLESHOOTING TIPS
DISCHARGE SUCTION
PRESSURE PRESSURE
High High
Low Low
Low Low
Low Low
High High
Low Low
Low High
Low Low
High High
INDICATORS
SUPERHEAT SUBCOOLING
Normal: 5°–15°F
[2.8° – 8.3°C] Charging Chart
Low
High
High
Low
Low
High
High
High
Low
INDICATORS
SUPERHEAT SUBCOOLING
Normal: 5°–15°F
[2.8° – 8.3°C] Charging Chart
OK
OK or High
High
Low
Low
OK
High
High
Low
Normal: See
High
Low
High
Low
Low
High
High
High
Low
Normal: See
High
Low
High
Low
Low
High
High
High
Low