Self-Diagnosis And Countermeasures Depending On The Check Code Displayed - Mitsubishi Electric CITY MULTI PUHY-80TMU-A Service Handbook

[2] Self-diagnosis and Countermeasures Depending on the Check Code Displayed

(1) Mechanical
Checking code Meaning, detecting method
0403 Serial If serial transmission cannot be
transmission established between the MAIN
and INV boards
trouble
1. When 140°C or more dis-
1102 Discharge
temperature charge temperature is de-
trouble tected during op-erations
(the first time), outdoor unit
(Outdoor unit) s t o p s o n c e , m o d e i s
changed to restart mode af-
ter 3 minutes, then the out-
door unit restarts.
2. When 140°C or more temp.
is detected again (the sec-
ond time) within 30 minutes
after stop of outdoor unit, er-
ror stop is observed with
code No. "1102" displayed.
3. When 140°C or more temp.
is detected 30 or more min-
utes after stop of outdoor
unit, the stop is regarded as
the first time and the process
shown in 1 is observed.
4. 30 minutes after stop of out-
door unit is intermittent fault
check period with LED dis-
played(1202).
Cause
1) Wiring is defective.
2) Switches are set wrong on the INV
board.
3) A fuse (F01) on the INV board is
defective.
4) The circuit board is defective.
1) Gas leak, gas shortage
2) Overload operations
3) Poor operations of indoor LEV
4) Poor operations of OC controller
LEV
Cooling : LEV1
5) Poor operations of ball valve
6) Outdoor unit fan block, motor
trouble, poor operations of fan
controller→Heating
3) ~ 6) : Rise in discharge
temp. by low pressure drawing
7) Gas leak between low and high
pressures
4-way valve trouble, compressor
trouble, solenoid valve SV1
trouble
8) Poor operations of solenoid valve
SV2
Bypass valve SV2 can not
control rise in discharge temp.
9) Thermistor trouble
10)Thermistor input circuit trouble on
control circuit board
- 62 -
Checking method & Countermeasure
Check 1, the connections, 2, contact
at the connectors and 3, for broken
wires in the following wiring.
CNRS2 - CNRS3
CNAC2 - TB1A
SW1-4 on the INV board should be
OFF.
If the fuse is melted, (if the resis-
tance between the both ends of fuse
is ∞), replace the fuse.
If none of the items in 1) to 3) is ap-
plicable, and if the trouble reappears
even after the power is switched on
again, replace the circuit board by
the following procedure (when re-
placing the circuit board, be sure to
connect all the connectors, ground
wires, etc. securely).
1 If serial transmission is restored
after the INV board only is re-
placed, then the INV board is de-
fective.
2 If serial transmission is not re-
stored, reinstall the INV board
and replace the MAIN board. If
serial transmission is restored,
the MAIN board is defective.
3 If serial transmission is not re-
stored by 1 and 2 above, re-
place both boards.
See Refrigerant amount check.
Check operating conditions and op-
eration status of indoor/outdoor
units.
Check operation status by actually
performing cooling or heating opera-
tions.
Cooling : Indoor LEV
LEV1
Heating : Indoor LEV
See Trouble check of LEV and so-
lenoid valve.
Confirm that ball valve is fully
opened.
Check outdoor fan.
See Trouble check of outdoor fan.
Check operation status of cooling or
heating.
See Trouble check of solenoid
valve.
Check resistance of thermistor
Check inlet temperature of sensor
with LED monitor.