Mitsubishi TPKA0A0241KA80A Service Manual page 14

9-3. SELF-DIAGNOSIS ACTION TABLE
Check code Abnormal point and detection method
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: 194°F [90:] or more
Open: −40°F [−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,
drying, and heating (except defrosting)
operation
Short: 194°F [90:] or more
P2
Open: −40°F [−40:] or less
Contact failure of drain float switch
(CN4F)
• Extract when the connector of drain float
switch is disconnected.
P4
(3 and 4 of connector CN4F is not
short-circuited.)
• Constantly detected during operation
Drain over flow protection operation
1 Suspensive abnormality, if drain float
switch is detected to be underwater for 1
minute and 30 seconds continuously with
drain pump on.
Compressor and indoor fan will be turned
off.
2 Drain pump is abnormal if the condition
P5
above is detected during suspensive
abnormality.
3 Constantly detected during drain pump
operation
TCHT011
Note:
Errors to be detected in outdoor unit, such as codes starting with F, U or E (excluding E0 to E7),
are not covered in this document. Please refer to the outdoor unit service manual for the details.
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 194°F [90:] or more, or
−40°F [−40:] or less.
5 Defective indoor controller
board
1 Contact failure of connector
(Insert failure)
2 Defective indoor controller
board
1 Malfunction of drain pump
2 Defective drain
Clogged drain pump
Clogged drain pipe
3 Defective drain float switch
Catch of drain float switch or
malfunction of moving parts
cause drain float switch to be
detected under water (Switch
On)
4 Defective indoor-controller
board
14
Countermeasure
1–3 Check resistance value of thermistor.
32°F [0:] ....15.0 k"
50°F [10:] ......9.6 k"
68°F [20:] ......6.3 k"
86°F [30:] ......4.3 k"
104°F [40:] ......3.0 k"
If you put force on (draw or bend) the lead
wire with measuring resistance value of
thermistor, breaking of wire or contact fail-
ure can be detected.
2 Check contact failure of connector (CN20)
on the indoor controller board. Refer to
"9-7. TEST POINT DIAGRAM".
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
"9-7. TEST POINT DIAGRAM".
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 Check contact failure of float switch connector.
Turn the power on again and check after insert-
ing connector again.
2 Operate with connector (CN4F) short-
circuited.
Replace indoor controller board if abnor-
mality reappears.
1 Check if drain-up machine works.
2 Check drain function.
3 Remove drain float switch connector
CN4F and check if it is short (Switch On)
with the moving part of float switch UP,
or OPEN with the moving part of float
switch down.
Replace float switch if it is short with the
moving part of float switch down.
4 Replace indoor controller board if it is
short-circuited between 3–4 of the drain
float switch connector CN4F and abnor-
mality reappears.
It is not abnormal if there is no problem about
the above-mentioned 1–4.
Turn the power off, and on again to operate after check.