Mitsubishi Electric PUHZ-W85VHA, Service Manual, Page: 19 / 45

19
Error Code
Abnormal point and detection method Judgment and action
Case
P6
Freezing/overheating protection is working
(1) Freezing protection <Cooling mode>
Abnormal if plate heat exchanger pipe
temperature (TH6) stays at -5
: or lower
for 10 seconds or abnormal if plate heat
exchanger pipe thermistor (TH6) stays at
-2
:
or lower and compressor operation
frequency is minimum for 5 minutes
after compressor starts operating for 6
minutes.
(2) Overheating protection <Heating mode>
Abnormal if condensing temperature of
pressure sensor (63HS) detects
Tcond.
:
or more and compressor oper-
ation frequency is less than or equal to
30 Hz. Detection is inoperative during
defrosting.
<Cooling mode>
1
Reduced water flow
· Clogged filter
· Leakage of water
2 Low temperature
· Low-load
· Inlet water is too cold.
3
Defective water pump
4
Defective outdoor fan control
5 Overcharge of refrigerant
6 Defective refrigerant circuit
(clogs)
7
Malfunction of linear expansion
valve
<Heating mode>
1
Reduced water flow
· Clogged filter
· Leakage of water
2 High temperature
· Over-load
· Inlet water is too warm.
3
Defective water pump
4
Overcharge of refrigerant
5
Defective refrigerant circuit
(clogs)
6 Malfunction of linear expansion
valve
<Cooling mode>
12
Check water piping.
3
Check water pump.
4
Check outdoor fan motor.
5
~
7
Check operating condition of refrigerant
circuit.
7 Check linear expansion valve.
<Heating mode>
12
Check water piping.
3
Check water pump.
45
Check operating condition of refrigerant
circuit.
6
Check linear expansion valve.
P8
UE
Abnormal pressure of pressure sensor
(63HS)
Abnormal if pressure sensor (63HS) detects
0.1 MPa or less.
Detection is inoperative for 3 minutes after
compressor starting and 3 minutes after
and during defrosting.
1
Disconnection or contact
failure of connector (63HS)
on the outdoor controller
circuit board
2
Defective pressure sensor
3
Defective outdoor controller
circuit board
1
Check connection of connector (63HS) on
the outdoor controller circuit board.
Check breaking of the lead wire for thermistor
(63HS).
2
Check pressure by microcomputer.
(Pressure sensor/ 63HS)
(SW2: Refer to 8-7.)
3
Replace outdoor controller board.
Pipe temperature
Abnormal if the following conditions are
detected for continuously 3 minutes after
compressor starts operating for 10 minutes.
1. Cooling mode
T
63HS
-TH7
[
2
:
and
TH3-TH7
[
4
:
or T
63HS
-TH3 < 0
:
and
TH32-TH6
[
0
:
and
Compressor operation frequency is 61Hz or more.
2. Heating mode
T
63HS
-TH32
[
2
:
and
TH6-TH32
[
1
:
and
TH7-TH3
[
1
:
and
Compressor operation frequency is 61Hz or more.
T
63HS
: Condensing temperature of pressure
sensor (63HS)
Thermistor
TH3: Liquid temperature
TH32: Inlet water temperature
TH6: Plate HEX Liquid temperature
TH7: Ambient temperature
1 Leakage or shortage of
refrigerant
2
Malfunction of linear
expansion valve
3 Refrigerant circuit is clogged
with foreign objects.
w
Clogging occurs in the parts
which become below freezing
point when water enters in
refrigerant circuit.
4 Disconnection of thermistor
holder.
1 Check intake superheat.
Check leakage of refrigerant.
2
Check linear expansion valve.
3 After recovering refrigerant, remove water
from entire refrigerant circuit under vacuum
more than 1 hour.
4 Check temperature display on outdoor
controller circuit board.
Temperature display is indicated by setting
SW2 of outdoor controller circuit board.
Check the holder of thermistor.
Ambient temperature (TH7)
-19
stage-g
stage-f
stage-e
stage-d
stage-c
stage-b
stage-a
-18 -16 -15 -13 -12 -11 -10 -8 -7 -3 -2
[ ]
Tcond
Tcond 63 61 59 57 54 51 48
stage-a stage-b stage-c stage-d stage-e stage-f stage-g