Carrier 42QZA009DS-1 Service Manual page 84

18.3.3.7 Current protection of compressor (ODU P3)
Current protection of compressor
Judge 1: Check whether the
input current of the power
supply wire is higher than max
protection current value
Yes
Check whether
the refrigerant
system is ok
Judge 2: Check whether the
outdoor ambient
temperature is higher than
50℃
No
Judge 3: Check whether the
outdoor unit is bad ventilation
No
Judge 4: Check whether the
heat exchanger is dirty
No
Judge 5: The refrigerant
pipe is blocked
No
Replace outdoor main
board,and check whether
the system can run normally
No
Replace the electric control box
Yes Stop the unit
Yes Make the outdoor unit ventilate well
Yes Clean the heat exchanger
Let the refrigerant out, then use the high
Yes pressure nitrogen or refrigerant to blow pipe,
vacuumize and charge the refrigerant again
Yes
Yes Trouble is solved
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