Mitsubishi Electric · R410A Systems
The high-pressure sensor (PSH) is either disconnected or its output signal is erroneous, indicating a fault in the sensor or its connection to the system. This specifically refers to the PSH.
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Inspect the PSH sensor's connector on the outdoor unit PCB — verify it is securely seated.
Measure the output voltage or resistance of the PSH sensor according to manufacturer specifications using a multimeter.
Check continuity of the wiring connecting the PSH sensor to the PCB.