Mitsubishi Electric PUZ-WM50VHA Service Manual page 31

Check code Abnormal points and detection method
Pipe temperature
Abnormal if the following conditions are
detected for continuously 3 minutes after
compressor starts operating for 10 minutes.
1. Cooling mode
TH6–TH7 [ 2: and
TH3–TH7 [ 4: or TH6−TH3 < 0: and
THW2(Indoor)-TH34 [ 0: and
Compressor operation frequency is 61 Hz or more.
2. Heating mode
T –THW2(Indoor) [ 2: and
63HS
P8 TH6–THW2(Indoor) [ 1: and
TH7–TH3 [ 1: and
Compressor operation frequency is 61 Hz or more.
T : Condensing temperature of pressure
63HS
sensor (63HS)
Thermistor
TH3: Liquid temperature
TH34: Plate HEX Liquid temperature
TH7: Ambient temperature
THW2(Indoor): Return water temp from
Indoorunit thermistor
Freezing/overheating protection is working
(1) Freezing protection
Plate HEX Liquid temperature(TH34) or
refrigerant saturation temperature is 10
seconds smaller than the threshold.The
threshold is dynamically calculated by
inner operation using the operating time
of the compressor and the water tem-
perature.
P6
Inlet water temperature
Abnormal if the following conditions are
detected for continuously 10 seconds.
1. Cooling mode
During compressor operation
THW2(Indoor) < 3:
2. Heating mode (exclude defrosting)
During compressor operation
PE
THW2(Indoor) < −10:
3. Defrosting mode
During compressor operation
THW2(Indoor) < 0:
Thermistor
THW2(Indoor): Return water temp from
OCH727
1 Leakage or shortage of
refrigerant
2 Malfunction of linear expansion
valve
3 Refrigerant circuit is clogged
with foreign objects.
Note: Clogging occurs in the
4 Disconnection of thermistor
holder.
(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 Leakage or shortage 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 expansion
valve
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
Indoorunit thermistor
Cause
1 Check intake superheat.
2 Check linear expansion valve.
3 After recovering refrigerant, remove water
parts which become below
freezing point when water
enters in refrigerant circuit.
4 Check temperature display on outdoor
(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
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.
12 Check water piping.
3 Check water pump.
4 Check intake superheat.
31
judgment and action
Check leakage of refrigerant.
from entire refrigerant circuit under vacuum
more than 1 hour.
controller circuit board.
Temperature display is indicated by setting
SW2 of outdoor controller circuit board.
Check the holder of thermistor.
circuit.
HOW TO CHECK THE COMPONENTS".
Check leakage of refrigerant.