Lennox MPA009S4S Service Manual page 103

Error Code:
E2
Description: Communication malfunction between outdoor unit and all indoor units.
General Note: Indoor unit does not receive the communication from outdoor unit for 120 seconds or outdoor unit does not receive the
communication from any one indoor unit for 180 seconds.
Start: Power off, then Power on the outdoor unit by
the Breaker. (reconnect the power wire). Is it still
displaying the error code?
Check wiring on the outdoor and indoor
terminals follow the wiring diagram. Are all
of the connections correct?
Turn on all indoor units by the remote
controller. Are all indoor units displaying
Turn off all of the indoor units. Is
IPM power LED operating LED
lamp on? Refer to Pic 2.
Is main board "88" lamp on?
Are the indoor units numbered correctly? Check
on the outdoor check point. (2 for 2-zone, 3 for
3-zone, 4 for 4-zone, 5 for 5-zone). Refer PIC 4.
Change outdoor unit PCB as-
sembly totally (include wiring).
E2
Yes
No
Yes
No
correctly?
Yes
Yes
No
Change IPM
Yes
Is the reactor
No
wiring properly
Refer Pic 3.
connected?
Yes
Change Outdoor Main PCB
No first time No second time
No
Correct the wiring
Reconnect the wiring
Measure Vs, is it moving alternately
between positive value and negative
value? (Vs is the voltage between 3
and 2). Refer Pic 1
No
Reconnect the
wiring
Yes
A
103
No
No
A: Is all the wiring between
terminals and indoor PCB
connected correctly`?
Yes
Change the Indoor PCB
Yes
Yes
Power on by remote controller, it is
still displaying the error code after
3 minutes?
No
Problem Solved