Mitsubishi Electric City Multi PQHY-P72 Service Handbook page 204

Error definition and error
Error Code
4240 Overload pro- When the greater output
tection current (Iac) than the
Imax (Arms), or THHS of
more than 90 °C [194°F]
is detected for 10 min-
utes in a row.
P72 model
P96 model
Refer to section -7-"Inverter " under part [4] "Trouble shooting principal parts" for error codes related to the inverter.
detection method
(1) Short cycle of the air pas-
sage
(2) Blocked air pathway
(3) Power supply
Imax
40 Arms
(4) Faulty wiring
50 Arms
(5) THHS failure
(6) Compressor INV board
cooling fan output failure
(7) Cooling failure
(8) Current sensor (ACCT)
failure
(9) Compressor Inverter cir-
cuit failure
(10) Compressor failure
- 195 -
Cause Check method and remedy
Check that the waste heat from the
heat source unit fan is not short cy-
cled.
Check for a clogged air passage.
Check whether the power supply
voltage is 187V or more.
Check for cooling fan wiring.
Check for THHS1 sensor resistor.
Confirm that a voltage of 208/230V
is applied to the compressor INV
board connector CNFAN during in-
verter operation.
Check the cooling fan operation un-
der the above operating conditions.
Refer to 9.[4].-7-.(4)
"Current sensor ACCT"
Refer to 9.[4].-7-.(2).[4].
"Check whether the inverter is dam-
aged".
Check that the compressor has not
overheated during operation.
-> Check the refrigerant circuit
(oil return section).
Replace the compressor
when no fault is found.
[ IX Troubleshooting ]