Toshiba Carrier MMD- AP0074BH2UL Service Manual page 68

Check code
Outdoor 7-segment display
Main
remote
controller Check code Sub-code
Detected
outdoor unit
No.
P19 P19
P20
P20
Location
of Description
detection
I/F 4-way valve
reversing error
I/F Activation of
high-pressure
protection
–
Error detection
System status
condition(s)
All stop Abnormal refrigerating cycle
data is collected during
heating operation.
All stop Pd sensor detects pressure
equal to or greater than
522psi(3.6MPa).
– 68 –
Check items (locations)
• Check for defect in main
body of 4-way valve.
• Check for coil defect in 4-
way valve and loose
connection of its
connector.
• Check resistance
characteristics of TS1 and
TE1 sensors.
• Check output voltage
characteristics of Pd and
Ps pressure sensors.
• Check for wiring error
involving TE1 and TL
sensors.
• Check for defect in Pd
pressure sensor.
• Check service valves (gas
side, liquid side) to confirm
full opening.
• Check for defect in outdoor
fan.
• Check for defect in outdoor
fan motor.
• Check outdoor PMVs
(PMV1, 2, 4) for clogging.
• Check indoor/outdoor heat
exchangers for clogging.
• Check for short-circuiting
of outdoor suction/
discharge air flows.
• Check SV2 circuit for
clogging.
• Check for defect in outdoor
P.C. board (I/F).
• Check for defect in indoor
fan system (possible cause
of air flow reduction).
• Check opening status of
indoor PMV.
• Check indoor-outdoor
communication line for
wiring error.
• Check for faulty operation
of check valve in discharge
pipe convergent section.
• Check gas balancing SV4
valve circuit.
• Check SV5 valve circuit.
• Check for refrigerant
overcharging.