Fujitsu FO20R Series Installation Instructions Manual page 66

9.0 DIAGNOSTICS & TROUBLESHOOTING
9.12 Service Analyzer Charts
High superheat
(greater than 15°F
[-8.3°C] at coil)
Low line voltage
High line voltage
High head
pressure
Short cycling of
compressor
66
Low charge
Verify suction thermistor operation (10k thermistor)
Verify pressure transducer operation input and
output voltage
Faulty metering device, inadequate suction
thermistor or pressure transducer operation.
High internal load
Restriction in liquid line
Low head pressure
Vapor or liquid line subjected to high heat
source
Loose wire connections
Power company problem, transformer
Undersized wire feeding unit
Power company problem
Overcharge
Dirty heat pump coil
Faulty or wrong size heat pump fan motor
Faulty fan blade or wrong rotation
Recirculation of air
Additional heat source
Noncondensibles
Equipment not matched
Cycling or faulty pressure control
Loose wiring
Thermostat
EXV restricted or not functioning properly
Distributor tube restricted
Check system charge.
Replace thermistor.
Replace thermistor and/or harness and/or control
board.
Restricted cap tube, EXV
Hot air (attic) entering return
Heat source on; miswired or faulty control
Drier plugged.
Line kinked.
Low charge
Operating in low ambient temperatures
Hot attic
Hot water line
Check wiring.
Report problem.
Correct and complete diagnosis.
Report problem.
Check system charge.
Clean coil.
Replace fan motor.
Replace fan blade.
Replace with correct rotation motor.
Correct installation.
Check for dryer vent near unit.
Check for recirculation from other equipment.
Recover refrigerant. Evacuate and recharge system.
Correct mismatch.
Check pressure and address cause of high or low
pressure. Replace pressure control if faulty.
Check unit wiring.
Located in supply air stream
Customer misuse
Internal foreign matter
Pressure transducer failure
Suction thermistor failure
EXV control failure
EXV coil failure
Restricted with foreign matter
Kinked
Inside diameter reduced from previous compressor failure