Carrier 40MPHA Service Manual page 28

E1 (Indoor and Outdoor Unit Communication Error)
Description: The indoor unit has not received feedback from the outdoor unit for 150 seconds, four consecutive times.
Recommended parts to prepare:
• Indoor PCB
• Outdoor PCB
• Reactor
Troubleshooting and Repair:
Power off. Wait 2 minutes then power back on.
Measure Vs . ( Vs is the voltage between S and N on
the outdoor unit. Red pan-S, Black pan -N)
alternately between positive and
The voltage moves alternately with
Check the outdoor wiring connection.
Replace the
reactor.
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Does the problem remain?
YES
Is the voltage moving
negative?
NO
positive value.
Is it normal?
YES
Check the reactor.
NO Is it normal?
YES
Replace the outdoor PCB.
Power on.
Is the error
resolved?
NO
Replace the indoor PCB.
Specifications subject to change without notice.
NO The unit is operating normally.
The voltage is a
NO
certain value.
Check the indoor wiring
connections.
Is it normal ?
Replace the indoor PCB.
Power on.
Is the error resolved?
Replace the outdoor PCB.
YES
NO
40MPHA-03SM