El 01 (Indoor And Outdoor Unit Communication Error Diag. And Solution) - MrCool DIY E Star Series Troubleshooting Manual

7.2 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
Does the error code
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/LN, Red pin to S).
For units with main PCB and IPM board
Check the AC voltage of L, N
output to IPM board, is it same
Unplug all the high voltage
components connected to main
PCB such as 4 way valve, heater,
AC fan one by one to check their
resistance . Is there any component
from IPM board to main
Unplug electronic expansion valve .
Check if the DC 5V, 12V to main
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.
minutes.
No
disappear ?
Yes
Correct the connection or
No
The value is alternative
from negative to positive
Yes
The value is fixed and close
The value is always positive
For units without W
wire
Check the wiring connection
from outdoor terminal to
both
outdoor PCB and wiring
between PCBs if there is
No Replace main PCB
as power input?
Yes
Yes
short circuit?
No
Check the DC 5V, 12V
PCB , are they normal?
No
Yes
PCB are OK
No
Replace IPM board
Solved
change wires
Check the wiring connection
from indoor terminal to indoor
to 0
For units
with W wire
For units with only one
PCB
more than 1 PCB
Replace outdoor PCB
Replace short-circuited
component and main
PCB
Yes
Replace short- circuited
component and outdoor
PCB
Replace coil of electronic
expansion valve
Troubleshooting 19
Replace indoor PCB
PCB, are they good?
Turn on the unit, check if W
and 1(L) is connected?
Yes
Check if the power LED is
Yes
on?
No
Unplug all the high voltage
components connected to main
PCB such as 4 way valve, heater,
Yes
AC fan one by one to check their
resistance . Is there any component
No
short circuit?
No
Unplug electronic expansion valve .
Yes
Check if power LED is on ?
No