Carrier 40MB C Series Service Manual page 28

Over voltage or too low voltage protection diagnosis and solution (P1)
Error Code
Malfunction decision conditions
Supposed causes
Check the power supply
Check the connections and
wires
Check the voltage between P
Check the reactor
Replace the reactor
P1
An abnormal voltage rise or drop is detected by checking the specified voltage detection
circuit.
S
Power supply problems
S
System leakage or block
S
PCB faulty
Yes
Yes
and N
Yes
Yes
Fig. 37 – Troubleshooting
Fig. 38 – Measure the DC voltage
Stop the unit
No
Correct the connections or
No
replace the wires.
No Replace the IPM board
Replace outdoor main PCB
No
28
Remark:
Measure the DC voltage
between P and N port.
The normal value should
be around 310V.