Mitsubishi Electric PAR-21MAA Technical Manual page 49

Indication
Outdoor controller board
LED (Green) LED2 (Red)
3 blinking  blinking Abnormality of shell thermistor (TH32)
and discharging temperature (TH4)
Abnormality of superheat due to low dis-
charge temperature
2 blinking Abnormal high pressure (High pressure
switch 63H worked.)
3 blinking Abnormality of outdoor fan motor rotational
speed
Protection from overheat operation (TH3)
4 blinking Compressor over current breaking (Start-up
locked)
Compressor over current breaking
Abnormality of current sensor (P.B.)
Abnormality of power module
5 blinking Open/short of discharge thermistor (TH4)
and shell thermistor (TH32)
Open/short of outdoor thermistors
(TH3, TH6, TH7 and TH8)
6 blinking Abnormality of heatsink temperature
7 blinking Abnormality of voltage
4 blinking  blinking Abnormality of room temperature thermis-
tor (TH)
Abnormality of pipe temperature thermistor
/Liquid (TH2)
Abnormality of pipe temperature thermis-
tor/Condenser-Evaporator
2 blinking Abnormality of drain sensor (DS)
Float switch (FS) connector open
Indoor drain overflow protectio
3 blinking Freezing (cooling)/overheating (heating)
protection
4 blinking Abnormality of pipe temperature
5 blinking Abnormality of Indoor controller board
— — Abnormality of remote controller board
W. Error code displayed on remote controller. Error codes given in ( ) are not displayed on remote controller.
Contents
Error
Error
code
W
U2
1Check if stop valves are open.
2Check if connectors (TH4, TH32, LEV-A and LEV-B) on
outdoor controller board are not disconnected.
U7
3Check if unit fills with specified amount of refrigeran
4Measure resistance values among terminals on indoor
valve and outdoor linear expansion valve with a tester.
U
1Check if indoor/outdoor units have a short cycle on
their air ducts.
2Check if connector (63H) on outdoor controller board is
not disconnected.
3Check if heat exchanger and filter is not dirt .
4Measure resistance values among terminals on linear
expansion valve with a tester.
U8
1Check the outdoor fan motor.
Ud
UF
1Check if stop valves are open.
2Check looseness, disconnection, and converse con-
nection of compressor wiring.
UP
3Measure resistance values among terminals on com-
UH
pressor with a tester.
U6
4Check if outdoor unit has a short cycle on its air duct.
U3
1Check if connectors (TH3, TH4, TH7/6, TH32) on out-
door controller board and connector (CN3) on outdoor
power board are not disconnected.
U4
2Measure resistance value of outdoor thermistors
U5
1Check if indoor/outdoor units have a short cycle on
their air ducts.
2Measure resistance value of outdoor thermistor(TH8).
U9
1Check looseness, disconnection, and converse con-
nection of compressor wiring.
2Measure resistance value among terminals on com-
pressor using a tester.
3Check the continuity of contactor (52C).
4Check if power supply voltage decreases.
5Check the wiring of CN52C.
6Check the wiring of CNAF.
P
1Check if connectors (CN20, CN2, CN29 and CN44)
on indoor controller board are not disconnected.
P2
2Measure resistance value of indoor thermistors.
P9
P4
1Check if connector (CN3,CN4F) on indoor controller
board is not disconnected.
P5
2Measure resistance value of indoor thermistors.
3Measure resistance value among terminals on drain-up
machine using a tester.
4Check if drain-up machine works.
5Check drain function.
P6
1Check if indoor unit has a short cycle on its air duct.
2Check if heat exchanger and filter is not dirt .
3Measure resistance value on indoor and outdoor fan
motors.
4Check if the inside of refrigerant piping is not clogged.
P8
1Check if indoor thermistors (TH2 and TH5) are not
disconnected from holder.
2Check if stop valve is open.
3Check converse connection of extension pipe. (on
plural units connection)
4Check if indoor/outdoor connecting wire is connected
correctly. (on plural units connection)
Fb
1Replace indoor controller board.
E, E2 1Replace the remote controller.
Inspection method
47