Mitsubishi Electric PSA-RP71GA Service Manual page 19

10-2. SELF-DIAGNOSIS ACTION TABLE
Abnormal point and detection method
Error Code
Room temperature thermistor (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
Open: -40: or less
P1
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
Drain sensor (DS)
1 Suspensive abnormality, if short/open
of thermistor is detected for 30 seconds
continuously.Compressor and indoor fan
will be turned off
2 Short/open is detected for 30 seconds
continuously during suspensive
abnormality.
(The unit returns to normal operation,
if it has normally reset.)
P4
3 Detect the following condition.
• During cooling and drying operation.
• In case that pipe <liquid> temperature -
room temperature <-10deg
(Except defrosting)
• When pipe <liquid> temperature or
room temperature is short/open
temperature.
• During drain pomp operation.
Malfunction of drain pump (DP)
1 Suspensive abnormality, if thermistor
of drain sensor is let heat itself and
temperature rises slightly. Compressor
and indoor fan will be turned off.
2 Drain pomp is abnormal if the condition
P5
above is detected during suspensive
abnormality.
3 Constantly detected during drain pump
operation.
Note: Refer to the manual of outdoor unit for the details of display
such as F, U, and other E.
Cause
1 Defective thermistor
characteristics
2 Contact failure of connector
(CN20) on the indoor controller
board (Insert failure)
3 Breaking of wire or contact
failure of thermistor wiring
4 Defective indoor controller
board
1 Defective thermistor
characteristics
2 Contact failure of connector
(CN44) on the indoor control-
ler board (Insert failure)
3 Breaking of wire or contact
failure of thermistor wiring
4 Defective refrigerant circuit is
causing thermistor tempera-
ture of 90: or more or -40:
or less.
5 Defective indoor controller
board
1 Defective thermistor
characteristics
2 Contact failure of connector
(CN31) on the indoor controller
board. (Insert failure).
3 Breaking of wire or contact
failure of drain sensor wiring.
4 Defective indoor controller board.
1 Malfunction of drain pump
2 Defective drain
Clogged drain pump
Clogged drain pipe
3 Attached drop of water at the
drain sensor
• Drops of drain trickles from
lead wire.
• Clogged filter is causing
wave of drain.
4 Defective indoor controller board.
19 19
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 connector (CN20)
on the indoor controller board. Refer to 10-6.
Turn the power on again and check restart
after inserting connector again.
4 Check room temperature display on remote
controller.
Replace indoor controller board if there is
abnormal difference with actual room
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 connector (CN44)
on the indoor controller board. Refer to 10-6.
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
extremely difference with actual pipe <liquid>
temperature, replace indoor controller board.
Turn the power off, and on again to operate
after check.
1–3 Check resistance value of thermistor.
0: ...... 6.0k"
10: .... 3.9k"
20: .... 2.6k"
30: .... 1.8k"
40: .... 1.3k"
2 Check contact failure of connector (CN31)
on the indoor controller board. Refer to 10-6.
Turn the power on again and check restart
after inserting connector again.
4 Replace indoor controller board if drain
pump operates with the line of drain sensor
connector CN31-1 and 2 is short-circuited,
and abnormality reappears.
Turn the power off, and on again to operate
after check.
1 Check if drain-up machine works.
2 Check drain function.
3 Check the setting of lead wire of drain sensor
and check clogs of the filter.
4 Replace indoor controller board if drain
pump operates with the line of drain sensor
connector CN31-1 and 2 is short-circuited
and abnormality reappears.
Refer to 10-6.
Turn the power off, and on again to operate
after check.