Mitsubishi Electric PUHZ-HRP200YKA Service Manual page 24

Error Code Abnormal point and detection method
Actual fl ow water temperature thermis-
tor (TH1)
1 The unit is in 3-minute resume
prevention mode if short/open of
thermistor is detected. Abnormal if the
unit does not reset normally after 3 min-
utes. (The unit returns to normal opera-
tion, if it has been reset normally.)
2 Constantly detected during cooling,
P1
heating ECO, anti freeze, hot water and
heating operation.
Short: -90: or more
Open: -40: or less
Pipe temperature thermistor/Liquid
(TH2)
1 The unit is in 3-minute resume
prevention mode if short/open of
thermistor is detected. Abnormal if the
unit does not reset normally after 3 min-
utes. (The unit returns to normal opera-
tion, if it has been reset normally.)
2 Constantly detected during cooling,
P2
heating ECO, anti freeze, hot water and
heating (except defrosting) operation
Short: 90: or more
Open: -40: or less
Freezing/overheating protection is working
1 Freezing protection (Cooling mode)
The unit is in 6-minute resume preven-
tion mode if pipe temperature stays
under -15: for 3 minutes, 3 minutes
after the compressor started. Abnormal if
it stays under -15: for 3 minutes again
within 16 minutes after 6-minute resume
prevention mode.
P6
2 Overheating protection (Heating, heating
ECO, Anti freeze, Hot water mode)
The units is in 6 minute resume preven-
tion mode if pipe temperature is detected
as over 70: after the compressor start-
ed. Abnormal if the temperature of over
70: is detected again within 30 minutes
after 6 minute resume prevention mode.
Actual tank temperature thermistor (TH5)
1 The unit is 3-minute resume preven-
tion mode if short/open of thermistor is
detected. 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, heat-
ing, heating ECO, anti freeze and hot
P9
water operation.
Cause
1 Defective thermistor
characteristics
2 Contact failure of TB61 No.1-2
on PCB of Interface unit/Flow
temp. controller
3 Breaking of wire or contact
failure of thermistor wiring
4 Defective PCB of Interface unit/
Flow temp. controller
1 Defective thermistor
characteristics
2 Contact failure of TB61 No.3-4
on PCB of Interface unit/Flow
temp. controller
3 Breaking of wire or contact
failure of thermistor wiring
4 Defective refrigerant circuit is
causing thermistor temperature
of 90: or more or -40: or
less.
5 Defective PCB of Interface unit/
Flow temp. controller
(Cooling mode)
1 Short cycle of air path
2 Low-load (low temperature) op-
eration out of the tolerance range
3 Defective outdoor fan control
4 Overcharge of refrigerant
5 Defective refrigerant circuit
(clogs)
(Heating mode)
1 Short cycle of air path
2 Over-load (high temperature) op-
eration out of the tolerance range
3 Defective outdoor fan control
4 Overcharge of refrigerant
5 Defective refrigerant circuit (clogs)
6 Bypass circuit of outdoor unit is
defective.
1 Defective thermistor character-
istics
2 Contact failure of TB61 No. 5-6
on PCB of interface unit/Flow
temp. controller
3 Breaking of wire or contact
failure of thermistor wiring
4 Defective PCB of interface
unit/Flow temp. controller
24
Judgment and action
1–3 Check resistance value of thermistor.
0: 15.0k"
10: 9.6k"
20: 6.3k"
30: 4.3k"
40: 3.0k"
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.
2 Check contact failure of TB61 No.1-2 on PCB
of Interface unit/Flow temp. controller. Refer to 8.
Turn the power on again and check restart
after inserting connector again.
4 Check actual fl ow water temperature display
on remote controller.
Replace PCB of Interface unit/Flow temp.
controller if there is abnormal difference with
actual fl ow water temperature.
Turn the power off, and on again to operate
after check.
1–3 Check resistance value of thermistor.
For characteristics, refer to (P1) above.
2 Check contact failure of TB61 No.3-4 on PCB of
Interface unit/Flow temp. controller. Refer to 8.
Turn the power on and check restart after
inserting connector again.
4 Check pipe <liquid> temperature with remote
controller in test run mode. If pipe <liquid>
temperature is extremely low (in cooling
mode) or high (in heating mode), refrigerant
circuit may have defective.
5 Check pipe <liquid> temperature with remote
controller in test run mode. If there is ex-
tremely difference with actual pipe <liquid>
temperature, replace PCB of Interface unit/
Flow temp. controller.
Turn the power off, and on again to operate
after check.
(Cooling mode)
1 Remove shields.
3 Check outdoor fan motor.
45 Check operating condition of refrigerant
circuit.
(Heating mode)
1 Remove shields.
3 Check outdoor fan motor.
4~6 Check operating condition of refrigerant
circuit.
1–3 Check resistance value of thermistor.
0: 15.0k"
10: 9.6k"
20: 6.3k"
30: 4.3k"
40: 3.0k"
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.
2 Check contact failure of TB61 No.5-6 on PCB of
Interface unit/Flow temp. controller. Refer to 8.
Turn the power on again and check restart
after inserting connector again.
4 Check actual tank temperature display on
remote controller.
Replace PCB of Interface unit/Flow temp.
controller if there is abnormal difference with
actual tank temperature.
Turn the power off, and on again to operate
after check.