Cooling - Mitsubishi Electric MXZ-4C36NAHZ Service Manual

Check code
1501
Abnormal points and detection methods
(1) Abnormal when all of the following conditions are satisfied:
1. The compressor is operating in HEAT mode.
2. Discharge super heat is 176°F [80 ] or more.
3. Difference between TH7 and the TH3 applies to the formula of
(TH7−TH3 < 41°F [5 ]).
4.The 63HS detects below 2.04 MPa.
(2) Abnormal when all of the following conditions are satisfied:
1.The compressor is in operation.
2.When cooling, discharge superheat is 176°F [80 ] or more.
3. When heating, discharge superheat is 194°F [90 ] or more.
4. The High-pressure sensor detects below 2.32 MPa
●Diagnosis of defectives
Make sure to turn the power OFF before connecting/disconnecting any connectors, or replacing boards.
Is the outdoor stop valve (ball
valve) fully open?
Is there a refrigerant leak?
Is 5104 displayed when restarted?
Check relevant thermistor wirings and
connector contacts of the controller
boards.
Is there any abnormality on
connectors such as a disconnection,
half-disconnection or breakage?
Disconnect the thermistor wiring and check
the resistance.
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OCH573
Refrigerant shortage trouble
Diagnosis
Yes
(leaking)
(no leaking)
No
(5104)
(1501)
No
No
Causes and check points
Defective operation of stop valve (not fully open)
Defective thermistor
Defective outdoor controller board
Indoor LEV performance failure
Gas leakage or shortage
Defective 63HS
TH3 : Thermistor <Outdoor liquid pipe>
TH7 : Thermistor <Ambient>
LEV : Electronic expansion valve
63HS : High-pressure sensor
Open the stop valve (ball balve) fully.
No
Repair the refrigerant leak.
Yes
Refer to the diagnosis of check code 5104.
Yes
Connect the connector properly.
Yes
(Repair or replace it in case of a breakage.)
49
Chart 1 of 2
Remedy