Carrier 40MPHA Service Manual page 24

DIAGNOSIS AND SOLUTION (CONT)
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:
S
Indoor PCB
S
Outdoor PCB
S
Reactor
Troubleshooting and Repair:
Power off , then restart the unit after 2 minutes.
Measure Vs . ( Vs is the voltage between S and N of
outdoor unit. Red pan-S, Black pan -N)
The voltage moves alternately with
Check the outdoor wiring connection .
Replace the
reactor
Does a problem remain ?
YES
Is the voltage moving
alternately between positive and
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 .
NO The unit is operating normally
The voltage is a
NO
certain value
Check the indoor wiring
connections
Is it normal ?
YES
Replace the indoor PCB .
Power on.
Is the error resolved ?
NO
Replace the outdoor PCB .
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