Carrier 38MBQ Series Service Manual page 22

DIAGNOSIS AND SOLUTION (CONT)
Table 19—Indoor/Outdoor Unit Communication Error − Diagnosis and Solution (E1)
Error Code
Malfunction decision conditions
Supposed causes
Troubleshooting:
Communication malfunction between
the indoor and outdoor units
Power off, wait for 2 minutes then
restart the unit. Does the problem
still exist?
Is there any interference such as
transformers? Or is the signal wire
Is the signal wire a shield cable
Are the signal wires properly
Replace the indoor main PCB, is the
error resolved?
Replace the outdoor main PCB.
E1
Indoor unit does not receive feedback from outdoor unit for 60 seconds, or the outdoor unit does
not receive feedback from indoor unit for 120 seconds.
S
Wiring mistakes
S
Faulty indoor or outdoor PCB
E1 displayed
Yes
too many lamps or power
too long?
No
and is the shield cable a
earthing?
Yes
Is the signal wire broken?
No
inserted on the PCB?
Yes
No
Remove the interference or add
Yes
a magnet ring on the power wire
Adopt a shield cable/shield cable
No
earthing
Replace the signal wire
Yes
Pull out and insert back
No
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