MrCool DIY E Star Series Installation & Owner's Manual page 45

10.2 Error Code: EL 01 (Indoor and outdoor unit communication error diagnosis and solution)
Description: Indoor unit can not communicate with outdoor unit
Recommended parts to prepare:
• Indoor PCB
• Outdoor PCB
• Short-circuited component
Troubleshooting and repair:
Power off, then restart the unit after
2 minutes.
Does the error
code disappear?
Check the
wiring connection
between indoor and
outdoor unit, are
they good?
Measure the DC voltage between N/L2
and S (Black pin to N/L2, Red pin to S).
For units with both a main PCB and IPM board
Check the AC voltage of L, N
output to IPM board, is it the
same as the power input?
Unplug all the high voltage components
connected to the main PCB such as a
4-way valve, heater, AC fan one by one
to check their resistance. Is there any
component short circuit?
Check the DC 5V, 12V from IPM
board to main PCB, are they normal?
Unplug electronic expansion valve.
Check if the DC 5V, 12V to main
PCB are OK.
Replace IPM board
The error codes and descriptions are for reference only. If your system displays any of
these codes contact a qualified technician to investigate the matter further.
NO Solved
YES
Correct the connection
NO
The value is alternative
from negative to positive.
YES
The value is fixed
and close to 0.
The value is
always positive
For units without W wire
Check the wiring connection from
the outdoor terminal to outdoor
PCB and wiring between PCBs if
there is more than 1 PCB.
Replace
NO
main PCB
YES
YES
YES
short-circuited
NO
component and
NO
YES
NO
****Disclaimer****
Note: For certain models, outdoor PCB
could not be removed separately. In this
case, the outdoor electric control box
should be replaced as a whole.
or change wires
Check the wiring connection
from indoor terminal to
indoor PCB, are they good?
For units with W wire
unit, check if W and 1(L)
are connected?
YES
For units with only one PCB
Replace
YES
outdoor PCB
Replace
short-circuited
component and
main PCB.
Replace
YES
outdoor PCB.
NO
Replace coil
YES
of electronic
expansion valve.
mrcool.com
Replace indoor
PCB
NO
Turn on the
Is the power
LED is on?
NO
Unplug all the high voltage
components connected to the main PCB
such as a 4-way valve, heater, AC fan
one by one to check their resistance.
Is there any component short circuit?
NO
Unplug electronic expansion valve.
Is power LED is on?
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