P2523 indicates that the powertrain control module (PCM) has detected a low voltage condition on the A/C request B circuit. This circuit carries the signal from the A/C control head or switch to the PCM, and a low reading typically means the signal is near ground when it should be at a higher voltage, preventing the A/C compressor from engaging.
The switch or control head that sends the A/C request signal to the PCM may be internally shorted to ground or failed, causing a constant low signal.
The signal wire between the A/C control and the PCM may be chafed, pinched, or otherwise shorted to ground, pulling the voltage low.
A broken wire, corroded connector, or poor terminal contact can cause the signal to be pulled low by the PCM's internal pull-down or reference circuit.
In very rare cases, an internal failure in the PCM's input circuit can cause a false low reading. This should only be considered after all wiring and switch tests pass.
No. P2523 is an electrical circuit fault for the A/C request signal, not a mechanical compressor issue. The compressor itself does not send this signal.
Almost never. The PCM is rarely the cause of this code. Most cases are due to a faulty A/C request switch, a shorted wire, or a poor connection. Only consider PCM replacement after thoroughly testing all other components and wiring.
Clearing the code may turn off the check engine light temporarily, but if the underlying low-voltage condition remains, the code will return as soon as the PCM rechecks the circuit. The root cause must be repaired.
No. P2523 is an electrical code related to the request signal circuit, not refrigerant pressure. However, some vehicles have a separate low-pressure switch that can prevent the request signal from being sent, but that would typically set a different code.