Mitsubishi Electric PUHZ-W90VHA Service Manual page 17

Abnormal point and detection method
Error Code
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.
P6
Tcond
stage-g
Pipe temperature
Abnormal if the following conditions are
detected for continuously 3 minutes after
compressor starts operating for 10 minutes.
1.Cooling mode
T -TH7 2
63HS
TH3-TH7 4 or T
TH32-TH6 0
Compressor operation frequency is 61Hz or more.
2.Heating mode
P8
T -TH32 2 and
63HS
TH6-TH32 1 and
TH7-TH3 1 and
Compressor operation frequency is 61Hz or more.
T :Condensing temperature of pressure
63HS
sensor(63HS)
Thermistor
TH3:Liquid temperature
TH32:Inlet water temperature
TH6:Plate HEX Liquid temperature
TH7:Ambient temperature
Abnormal pressure of pressure sensor
(63HS)
Abnormal if pressure sensor(63HS) detects
0.1MPa or less.
UE
Detection is inoperative for 3 minutes after
compressor starting and 3minutes after
and during defrosting.
<Cooling mode>
· Clogged filter
· Leakage of water
· Low-load
· Inlet water is too cold.
<Heating mode>
· Clogged filter
· Leakage of water
· Over-load
· Inlet water is too warm.
stage-e
stage-f
-19 -18 -16 -15 -13 -12
stage-a stage-b stage-c stage-d stage-e stage-f stage-g
Tcond 63
and
-TH3< 0 and
63HS
and
Case
Reduced water flow
Low temperature
Defective water pump
Defective outdoor fan control
Overcharge of refrigerant
Defective refrigerant circuit
(clogs)
Malfunction of linear expansion
valve
Reduced water flow
High temperature
Defective water pump
Overcharge of refrigerant
Defective refrigerant circuit
(clogs)
Malfunction of linear expansion
valve
stage-b
stage-c
stage-d
-11 -10 -8 -7
Ambient temperature (TH7)
61 59 57 54
Leakage or shortage of
refrigerant
Malfunction of linear
expansion valve
Refrigerant circuit is clogged
with foreign objects.
Clogging occurs in the parts
which become below freezing
point when water enters in
refrigerant circuit.
Disconnection holder of
thermistor
Disconnection or contact
failure of connector (63HS)
on the outdoor controller
circuit board
Defective pressure sensor
Defective outdoor controller
circuit board
17
Judgment and action
<Cooling mode>
Check water piping.
Check water pump.
Check outdoor fan motor.
~ Check operating condition of refrigerant
circuit.
Check linear expansion valve.
<Heating mode>
Check water piping.
Check water pump.
Check operating condition of refrigerant
circuit.
Check linear expansion valve.
stage-a
-3 -2
[ ]
51 48
Check intake superheat.
Check leakage of refrigerant.
Check linear expansion valve.
After recovering refrigerant, remove water
from entire refrigerant circuit under vacuum
more than 1 hour.
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.
Check connection of connector (63HS) on
the outdoor controller circuit board.
Check breaking of the lead wire for thermistor
(63HS).
Check pressure by microcomputer.
(Pressure sensor/ 63HS)
(SW2: Refer to 8-7.)
Replace outdoor controller board.