38MARB: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
28
DIAGNOSIS AND SOLUTION (CONT)
Indoor and Outdoor Unit Communication Error (EL01)
Description:
The indoor unit cannot communicate with the outdoor unit
Recommended parts to repair:
• Indoor PCB
• Outdoor PCB
• Short-circuited component
Troubleshooting:
For certain models, outdoor PCB could not be removed separately. In this case, the outdoor electric control box should be replaced as a whole.
Does the error code
disappear?
Power off, then restart the unit after 2
minutes.
Measure the DC voltage between N/L2
and S (red pin to N/L2, black pin to S).
The value is fixed and close
to 0.
The value is alternative
from negative to positive.
The value is always positive
Check the wiring connection
between the indoor and
outdoor units.
Are they OK?
between the indoor and outdoor
Check the wiring connection
from outdoor terminal to
outdoor PCB and wiring
between PCBs if there is
more than 1 PCB
Check the wiring connection
from indoor terminal to indoor
PCB. Are they OK?
Turn on the unit, check if W
and 1(L) are connected.
Check that the power
LED is on.
No
Yes
Yes
Unplug all the high voltage
components connected to the
main PCB ( 4-way valve, heater,
AC fan) one by one to check
their resistance. Has any
component short circuit?
Unplug the electronic expansion
valve. Check if the power LED is on.
No
No
Check the AC voltage of L, N
output to IPM board. Is it the
same as the power input?
Check the DC 5V, 12V
from IPM board to main
PCB. Are they OK?
Unplug all the high voltage
components connected to main
PCB (4 way valve, heater, AC fan)
one by one to check their resistance.
Has any component short circuited?
Yes
No
Unplug electronic expansion valve.
Check if the DC 5V, 12V to the main
PCB are ok.
Replace short-circuited
component and main
PCB.
PCB
Replace the electronic
expanson valve coil.
Replace the
outdoor PCB.
Replace the short
-circuited component
and the outdoor PCB.
PCB
Yes
Yes
Yes
Yes
Replace the
main PCB.
No
Yes
No
Replace the IPM board.
No
Replace the
indoor PCB.
No
Solved
Correct the connection or
change wires.
No
Yes
Yes
For units with main PCB and IPM board both.
For units with only one PCB
For units
with W wire
For units without W wire
No
