Mitsubishi Electric PUHZ-W50VHA Service Manual page 61

Check Code Abnormal point and detection method
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 com-
pressor operation frequency is mini-
mum for 5 minutes after compressor
starts operating for 6 minutes.
<Heating mode>
Abnormal if inlet water temperature
P6
thermistor (TH32) is 15: or lower,
and the following condition (1 or 2) are
detected.
1. 1 minute has passed since defrost-
ing operation started and plate heat
exchanger pipe temperature thermistor
(TH6) stays at −6: or lower for con-
tinuously 30 seconds.
2. During defrosting operation and plate
heat exchanger pipe temperature ther-
mistor (TH6) stays at −16: or lower
for continuously 10 seconds.
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: and
63HS−
TH3−TH7 [ 4: or T
TH32−TH6 [ 0: and
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 pres-
63HS
sure 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 0.1 MPa or less.
UE Detection is inoperative for 3 minutes after
compressor starting and 3 minutes after
and during defrosting.
Inlet water temperature
Abnormal if the following conditions are
detected for continuously 10 seconds.
1. Cooling mode
During compressor operation
TH32 < 3:
2. Heating mode (exclude defrosting)
PE
During compressor operation
TH32 < −10:
3. Defrosting mode
During compressor operation
TH32 < 0:
Thermistor
TH32: Inlet water temperature
OCH439M
(1) Freezing protection
<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 Low temperature
· Low-load
· Inlet water is cold.
3 Defective water pump
4 Leakage or shortage of refrigerant
5 Malfunction of linear expan-
sion valve
1 Leakage or shortage of
refrigerant
2 Malfunction of linear expansion
valve
−TH3 < 0: and
3 Refrigerant circuit is clogged
63HS
with foreign objects.
Note: Clogging occurs in the
parts which become below
freezing point when water
enters in refrigerant circuit.
4 Disconnection of thermistor
holder
1 Disconnection or contact fail-
ure of connector (63HS) on
the outdoor controller circuit
board
2 Defective pressure sensor
3 Defective outdoor controller
circuit board
1 Reduced water flow
· Clogged filter
· Leak of water
2 Low temperature
· Low-load
· Low temperature inlet water
3 Defective water pump
4 Leakage or shortage of refrig-
erant
61
Cause
(1) Freezing protection
<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.
4 Correct to proper amount of refrigerant.
5 Check linear expansion valve. Refer to "9-5.
HOW TO CHECK THE COMPONENTS".
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.
1 Check connection of connector (63HS) on
the outdoor controller circuit board.
Check breaking of the lead wire for thermis-
tor (63HS).
2 Check pressure by microprocessor. (Pressure
sensor/ 63HS) (SW2: Refer to "9-7.
OUTDOOR UNIT OPERATION MONITOR
FUNCTION".)
3 Replace outdoor controller board.
12 Check water piping.
3 Check water pump.
4 Check intake superheat.
Check leakage of refrigerant.
Judgment and action