Self-Diagnosis Action Table - Mitsubishi Electric Mr.SLIM PKA-A12GA Service Manual

10-3. SELF-DIAGNOSIS ACTION TABLE

Abnormal point and detection method
Error Code
Room temperature thermistor (TH1)
1 The unit is in 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, dry-
ing, and heating operation.
Short: -90:(194˚F) or more
P1
Open: -40:(-40˚F) 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:(194˚F) or more
Open: -40:(-40˚F) or less
Drain sensor (DS)
1 Suspensive abnormality, if short/open
of thermistor is detected for 30 seconds
continuously.
Turn off compressor and indoor fan.
2 Short/open is detected for 30 seconds con-
tinuously during suspensive abnormality.
(The unit returns to normal operation, if
it has been reset normally.)
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 tem-
perature.
• During drain pump operation
Malfunction of drain pump (DP)
1 Suspensive abnormality, if thermistor
of drain sensor heats itself and
temperature rises slightly. Turn off
compressor and indoor fan.
2 Drain pump 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
(CN21) on the indoor controller
board (Insert failure)
3 Breaking of wire or contact
failure of thermistor wiring
4 Defective refrigerant circuit is
causing thermistor temperature
of 90:(194˚F) or more or
-40:(-40˚F) 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
24
Countermeasure
1–3 Check resistance value of thermistor.
0: (32˚F) 15.0k"
• • • • • • • • • • •
10:(50˚F) 9.6k"
• • • • • • • • • • • • •
20:(68˚F) 6.3k"
• • • • • • • • • • • • •
30:(86˚F) 4.3k"
• • • • • • • • • • • • •
40:(104˚F) 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 connector (CN20)
on the indoor controller board. Refer to 10-7.
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 abnor-
mal 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 (CN21)
on the indoor controller board. Refer to 10-7.
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 defect.
5 Check pipe <liquid> temperature with remote
controller in test run mode. If there is extreme
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: (32˚F) 6.0k"
• • • • • • • • • • • •
10:(50˚F) 3.9k"
• • • • • • • • • • • •
20:(68˚F) 2.6k"
• • • • • • • • • • • •
30:(86˚F) 1.8k"
• • • • • • • • • • • •
40:(104˚F) 1.3k"
• • • • • • • • • •
2 Check contact failure of connector (CN31)
on the indoor controller board. Refer to 10-7.
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 pump 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 10-7.
Turn the power off, and on again to operate
after check.