P9; Pl; Abnormal Refrigerant Circuit; Remote Controller Transmission - Mitsubishi Electric Mr.Slim PKA Series Service Manual

Abnormal point and detection method
Check code
Pipe temperature thermistor/
Condenser-Evaporator (TH5)
1 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.)
2 Constantly detected during cooling,
drying, and heating operation (except
defrosting)
Short: 90: or more
Open: −40: or less

P9

Abnormal refrigerant circuit

During Cooling, Dry, or Auto Cooling
operation, the following conditions are
regarded as failures when detected for 1
second.
a) The compressor continues to run for 30
or more seconds.
b) The liquid pipe temperature or the

PL

condenser/evaporator temperature is
75°C or more.
These detected errors will not be
cancelled until the power source is
reset.

Remote controller transmission

error(E0)/signal receiving error(E4)
1 Abnormal if main or sub remote con-
troller cannot receive any transmission
normally from indoor unit of refrigerant
address "0" for 3 minutes.
(Check code: E0)
2 Abnormal if sub remote controller could
not receive any signal for 2 minutes.
(Check code: E0)
1 Abnormal if indoor controller board
cannot receive any data normally from
E0
remote controller board or from other
or
indoor controller board for 3 minutes.
E4
(Check code: E4)
2 Indoor controller board cannot receive
any signal from remote controller for 2
minutes. (Check code: E4)
OCH758
Cause
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 Temperature of thermistor is
90: or more or −40: or less
caused by defective refrigerant
circuit.
5 Defective indoor controller
board
Abnormal operation of 4-way
valve
Disconnection of or leakage in
refrigerant pipes
Air into refrigerant piping
Abnormal operation (no
rotation) of indoor fan
· Defective fan motor.
· Defective indoor control
board.
Defective refrigerant circuit
(clogging)
1 Contact failure at transmission
wire of remote controller
2 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 controller
circuit board.
3 Miswiring of remote controller
4 Defective transmitting receiving
circuit of remote controller
5 Defective transmitting receiving
circuit of indoor controller board
of refrigerant addresses "0".
6 Noise has entered into the
transmission wire of remote
controller.
19
Countermeasure
1–3 Check resistance value of thermistor.
For characteristics, refer to (P1).
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 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 cooling mode) or high (in
heating mode), refrigerant circuit may have
defect.
5 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 case of checking pipe temperature
(
with outdoor controller circuit board,
be sure to connect A-control service
tool (PAC-SK52ST).
When this error occurs, be sure to
replace the 4-way valve.
Check refrigerant pipes for disconnection or
leakage.
After the recovery of refrigerant, vacuum
dry the whole refrigerant circuit.
Refer to "9-6-2. DC fan motor (fan motor/
indoor controller circuit board".
Check refrigerant circuit for operation.
To avoid entry of moisture or air into
refrigerant circuit which could cause
abnormal high pressure, purge air in
refrigerant circuit or replace refrigerant.
1 Check disconnection or looseness of indoor
unit or transmission wire of remote controller.
2 Set one of the remote controllers "main"
if there is no problem with the action above.
3 Check wiring of remote controller.
• Total wiring length: maximum 500 m
(Do not use cable with 3 or more cores.)
• The number of connecting indoor units:
maximum 16 units
• The number of connecting remote control-
ler: maximum 2 units
When it is not the above-mentioned problem of
1–3
4 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 "ERC" is displayed, noise
may be causing abnormality.
Note:
If the unit is not normal after replacing indoor
controller board in group control, indoor control-
ler board of address "0" may be abnormal.
)