Mitsubishi Electric PUHZ-W50VHA Technical Manual page 78

[ 1 ] SELF-DIAGNOSIS ACTION TABLE
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,
drying, and heating operation.
Short: -90: or more
P1
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
drying, and heating (except defrosting)
operation
Short: 90: or more
Open: -40: or less
Freezing/overheating protection is work-
ing
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 mode)
The units is in 6 minute resume
prevention mode if pipe temperature is
detected as over 70: after the compres-
sor started. Abnormal if the temperature
of over 70: is detected again within 30
minutes after 6 minute resume preven-
tion mode.
Error code indication
You can check an error code on both 1 and 2.
1 LCD display on remote controller
2 2-digit LED indicator on outdoor unit PCB
(For SPLIT type outdoor unit, this LED indicator is optional parts.PAC-SK52ST)
* The 2-digit LED indicator on outdoor unit PCB can display indoor side error as well.
Cause
1 Defective thermistor
characteristics
2 Contact failure of TB61 No.1-2
on PCB of FTC
3 Breaking of wire or contact
failure of thermistor wiring
4 Defective PCB of FTC
1 Defective thermistor
characteristics
2 Contact failure of TB61 No.3-4
on PCB of FTC
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 FTC
(Cooling mode)
1 Short cycle of air path
2 Low-load (low temperature)
operation 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)
operation 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.
78
Countermeasure
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 thermis-
tor, breaking of wire or contact failure can be
detected.
2 Check contact failure of TB61 No.1-2 on
PCB of FTC. 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 FTC if there is abnormal dif-
ference 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 FTC. 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 FTC.
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.