Mitsubishi Electric PUHZ-SW50VHA Service Manual page 28

Check Code Abnormal points and detection method
Freezing/overheating protection is operat-
ing
Overheating protection <Heating mode>
Abnormal if condensing temperature of
pressure sensor (63HS) detects
Tcond. °C or more and compressor
operation frequency is less than or equal
to 25 Hz. Detection is inoperative during
defrosting.
Tcond
P6
stage-g
−18 −17
Tcond
SW40/50
Actual tank temperature thermistor (TH5/
THW5)
1 The unit is 3-minute resume prevention
mode if short/open of thermistor is de-
tected. Abnormal if the unit does not reset
normally after 3 minutes. (The unit returns
to normal operation, if it has been reset
normally.)
2 Constantly detected during cooling,
heating, heating ECO, anti freeze and hot
water operation.
P9
OCH525C
1 Overcharge of refrigerant
2 Defective refrigerant circuit (clogs)
3 Malfunction of linear expansion valve
4 Reduced water flow
· Clogged filter
· Leakage of water
5 High temperature
· Over-load
· Inlet water is too warm.
6 Defective water pump
stage-d
stage-e
stage-f
−15 −14 −12 −11
stage-a stage-b stage-c stage-d stage-e stage-f stage-g
63 61 60
1 Defective thermistor characteris-
tics
2 Breaking of wire or contact failure
of thermistor wiring
3 Defective PCB of interface unit/
Flow temp. controller
Case
12 C heck operating condition of refrigerant
3 Check linear expansion valve.
45 Check water piping.
6 Check water pump.
stage-b
stage-c
−9 −8 −6 −5
58 56 53 50
1–2 Check resistance value of thermistor.
If you put force on (draw or bend) the lead
wire with measuring resistance value of
thermistor, breaking of wire or contact failure
can be detected.
3 Check actual tank temperature display on
Replace PCB of Interface unit/Flow temp.
28
Judgment and action
circuit.
stage-a
stage-s
27 28
−3 −2
Ambient temperature (TH7)
stage-s
61
0: 15.0 k"
9.6 k"
10:
20: 6.3 k"
4.3 k"
30:
3.0 k"
40:
remote controller.
controller if there is abnormal difference
with actual tank temperature.
Turn the power off, and on again to oper-
ate after check.
Refer to the indoor unit's Installation Manual
for TH5 connection.
[°C]