Mitsubishi Electric PVA-A30AA4 Service Manual page 26

12-3. SELF-DIAGNOSIS ACTION TABLE
Abnormal point and detection method
Error Code
Room temperature
thermistor (TH1)
1 The unit is in three-minute resume
prevention mode if short/open of
thermistor is detected. Abnormal if the
unit does not reset normally after three
minutes. (The unit returns to normal
operation, if it has normally reset.)
2 Constantly detected during cooling,
drying and heating operation
Short: 90˚C[194˚F] or more
Open: -40˚C[-40˚F] or less
P1
Pipe temperature
thermistor/Liquid (TH2)
1 The unit is in three-minute resume
prevention mode if short/open of
thermistor is detected. Abnormal if the
unit does not reset normally after three
minutes. (The unit returns to normal
operation, if it has normally reset.)
2 Constantly detected during cooling,
drying, and heating (except defrosting)
operation.
Short: 90˚C[194˚F] or more
P2
Open: -40˚C[-40˚F] or less
Contact failure of drain float switch (CN4F)
1 Extract when the connector of drain float
switch is disconnected.
(3 and 4 of connector CN4F is not
short-circuited.)
2 Constantly detected during operation.
P4
(5701)
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 controller
board (Insert failure)
3 Breaking of wire or contact
failure of thermistor wiring
4 Defective refrigerant circuit is
causing thermistor temperature
of 90˚C[194˚F] or more or
-40˚C[-40˚F] or less.
5 Defective indoor controller board
1 Contact failure of connector
(Insert failure)
2 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 12-5.
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 12-5.
Turn the power on again 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 extreme
difference with actual pipe <liquid> temperature,
replace indoor controller board.
Turn the power off, and on again to operate
after check.
1 Check contact failure of float switch connec-
tor.
Turn the power on again and check after
inserting connector again.
2 Operate with connector (CN4F) short-circuited.
Refer to 12-5. Replace indoor controller
board if abnormality reappears.