Mitsubishi Electric EHGT17D-YM9ED Service Manual page 71

Indication
Controller circuit board
LED1 (Green) LED2 (Red)
3 blinking 1 blinking Abnormality of discharge temperature
(TH4) and Comp. surface temperature
(TH33)
Abnormality of superheat due to low
discharge temperature
2 blinking Abnormal high pressure (High pressure
switch 63H operated.)
Abnormal low pressure
Abnormal low brine flow rate (flow switch
operated)
3 blinking Abnormality of brine pump motor
rotational speed
Protection from overheat operation (TH3) Ud
4 blinking Compressor overcurrent breaking (Start-
up locked)
Compressor overcurrent breaking
Abnormality of current sensor (P.B.)
Abnormality of power module
5 blinking Open/short of heat pump unit thermistors
(TH4, TH33)
Open/short of heat pump unit thermistors
(TH3, TH32, TH34, TH7 and TH8)
6 blinking Abnormality of heat sink temperature
7 blinking Abnormality of voltage
4 blinking 1 blinking Abnormality of room temperature
thermistor (TH1)
Abnormality of pipe temperature
thermistor /Liquid (TH2)
Abnormality of tank temperature
thermistor
4 blinking Abnormality of pipe temperature
* Check code displayed on remote controller
** Refer to service manual for indoor unit.
OCH722A
Check
Contents
code*
U2
U7
U1
UL
UA
U8
UF
UP
UH
U6
U3
U4
U5
U9
P1
P2
P9
P8
71
Error
Inspection method
1 Check if stop valves are open.
2 Check if connectors (TH4, LEV-A) on controller
circuit board are not disconnected.
3 Check if unit is filled with specified amount of
refrigerant.
4 Measure resistance values among terminals
on linear expansion valve using a tester.
1 Check if connector(63H)(63L) on controller
circuit board is not disconnected.
2 Check if filter is not dirty.
3 Measure resistance values among terminals
on linear expansion valve using a tester.
1 Check the brine pumpmotor.
2 Check if connector (TH3) (63HS) on controller
circuit board is disconnected.
1 Check looseness, disconnection, and
converse connection of compressor wiring.
2 Measure resistance values among terminals
on compressor using a tester.
3 Check leakage of refrigerant.
1 Check if connectors (TH3, TH32, TH34, TH4,
TH33 and TH7) on controller circuit board and
connector (CN3) on power circuit board are
not disconnected.
2 Measure resistance value of heat pump unit
thermistors.
1 Measure resistance value of outdoor
 thermistor(TH8).
1 Check looseness, disconnection, and
converse connection of compressor wiring.
2 Measure resistance value among terminals on
compressor using a tester.
3 Check if power supply voltage decreases.
4 Check the wiring of X52CA.
5 Check the wiring of CNAC.
1 Check if connectors on FTC are not
disconnected.
2 Measure resistance value of FTC thermistors.
1 Check if FTC thermistors(TH2) are not
disconnected from holder.
2 Check if stop valve is open.
Detailed
reference
page
P46
P47
P46
P48
P48
P47
─
P48
P48
P48
P47
P46
P47
P47
P47-
P48
P44
P44
─
─