Mitsubishi Electric Mr. SLIM PCA-M71HA2 Service Manual page 15

Check Code Abnormal point and detection method
Pipe temperature
<Cool mode>
Detected as abnormal when the pipe tem-
perature is not in the cooling range 3 min-
utes after compressor start and 6 minutes
after the liquid or condenser/evaporator
pipe is out of cooling range.
Note 1: It takes at least 9 minutes to
detect.
Note 2: Abnormality P8 is not detected in
dry mode.
Cooling range: −3 °C ≥ (TH−TH1)
TH: Lower temperature between liquid pipe
temperature (TH2) and condenser/
evaporator temperature (TH5)
P8 TH1: Intake temperature
<Heat mode>
When 10 seconds have passed since the
compressor starts operation and the hot
adjustment mode has finished, the unit is
detected as abnormal when condenser/
evaporator pipe temperature is not in heat-
ing range within 20 minutes.
Note 3: It takes at least 27 minutes to
detect abnormality.
Note 4: It excludes the period of defrosting.
(Detection restarts when defrost
mode is over.)
Heating range: 3 °C ≤ (TH5−TH1)
Pipe temperature thermistor/
Condenser-Evaporator (TH5)
The unit is in 3-minute resume protec-
tion mode if short/open of thermistor is
detected. Abnormal if the unit does not
get back to normal within 3 minutes. (The
unit returns to normal operation, if it has
been reset normally.)
Constantly detected during cool, dry,
and heat (except defrost)
Short: 90°C or more
Open:−40°C or less
P9
Remote controller transmission
error(E0)/signal receiving error(E4)
Abnormal if main or sub remote control-
ler cannot receive any transmission
normally from indoor unit of refrigerant
address "0" for 3 minutes.
(Check code: E0)
Abnormal if sub remote controller could
not receive any signal for 2 minutes.
(Check code: E0)
Abnormal if indoor controller board can
E0
not receive any data normally from
or
remote controller board or from other
E4
indoor controller board for 3 minutes.
(Check code: E4)
Indoor controller board cannot receive
any signal from remote controller for 2
minutes. (Check code: E4)
OCH753A
Cause
Slight temperature difference
between indoor room
temperature and pipe <liquid
or condenser/ evaporator>
temperature thermistor
• Shortage of refrigerant
• Disconnected holder of
pipe <liquid or condenser/
evaporator> thermistor
• Defective refrigerant circuit
Reverse connection of
extension pipe (on plural units
connection)
Reverse wiring of indoor/
outdoor unit connecting wire
(on plural units connection)
Defective detection of indoor
room temperature and pipe
<condenser/evaporator>
temperature thermistor
Stop valve is not opened
completely.
Defective thermistor
characteristics
Contact failure of connector
(CN29) on the indoor control-
ler board (Insert failure)
Breaking of wire or contact
failure of thermistor wiring
Temperature of thermistor is
90°C or more or −40°C or less
caused by defective refrigerant
circuit.
Defective indoor controller
board
Contact failure at transmission
wire of remote controller
All remote controllers are set
as "sub" remote controller.
In this case, E0 is displayed
on remote controller, and E4
is displayed at LED (LED1,
LED2) on the outdoor control-
ler circuit board.
Miswiring of remote controller
Defective transmitting receiv-
ing circuit of remote controller
Defective transmitting receiv-
ing circuit of indoor controller
board of refrigerant addresses
"0".
Noise has entered into the
transmission wire of remote
controller.
15
Judgment and action
– Check pipe <liquid or condenser/evapora-
tor> temperature with room temperature
display on remote controller and outdoor
controller circuit board.
Pipe <liquid or condenser/evaporator>
temperature display is indicated by set-
ting SW2 of outdoor controller circuit
board as follows.
(
Conduct temperature check with outdoor
controller circuit board after connecting
'A-Control Service Tool (PAC-SK52ST)'.
Check reverse connection of extension
pipe or reverse wiring of indoor/outdoor
unit connecting wire.
Check the stop valve is opened completely.
Check resistance value of thermistor.
For characteristics, refer to (P1).
Check contact failure of connector (CN29) on
the indoor controller board.
Refer to "9-7. TEST POINT DIAGRAM".
Turn the power on and check restart after
inserting connector again.
Operate in test run mode and check pipe
<condenser/evaporator> temperature with
outdoor controller circuit board. If pipe
<condenser / evaporator> temperature is
extremely low (in cool mode) or high (in heat
mode), refrigerant circuit may have defect.
Operate in test run mode and check pipe
<condenser / evaporator> temperature with
outdoor control circuit board. If there is
extreme difference with actual pipe
<condenser / evaporator> temperature,
replace indoor controller board.
There is no abnormality if none of above
comes within the unit.
( Turn the power off and on again to operate.
In the case of checking pipe tem-
perature with outdoor controller circuit
board, be sure to connect A-control
service tool (PAC-SK52ST).
Check disconnection or looseness of indoor
unit or transmission wire of remote controller.
Set one of the remote controllers "main"
if there is no problem with the action above.
Check wiring of remote controller.
• Total wiring length: max. 500 m
(Do not use cable with 3 or more cores.)
• The number of connecting indoor units:
max. 16 units
• The number of connecting remote control-
ler: max. 2 units
If the cause of trouble is not any of
diagnose – by remote controllers.
– Diagnose remote controllers
a) When "OK" is displayed,
remote controllers have no problem.
Turn the power off, and on again to check.
If abnormality occurs again, replace indoor
controller board.
b) When "NG" is displayed,
replace remote controller.
c) When "E3" or "00-66" is displayed, noise
may be causing abnormality.
Note:
If the unit is not normal after replacing indoor
controller board in group control, indoor con-
troller board of address "0" may be abnormal.
)
)
– above,