Turbo Air TAS-18EHN Service Manual page 52

9.2.6 Over voltage or over low voltage protection diagnosis and solution (P1)
Check if the power supply is
normal.
Yes
Check if all the connections
and wires are good?
Yes
Power on and when the unit is in
standby, check if the voltage
between P and N is around DC
310V or 340V or 380V? For different
kinds of units, the voltage differs.
Consult with technical engineer to
get definite value. Then start up the
unit, measure the voltage between
P and N. Is it in 220V~400V?
Yes
Replace outdoor mainl PCB.
Disconnect the unit with power
No supply and try to restart the unit
when power supply gets normal.
Correct the connections or replace
No
Replace the IPM board if it is separate
No
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the wires.
with main PCB.