The P2520 code indicates that the engine control module (PCM) has detected a voltage signal below the expected threshold on the air conditioning request circuit. This typically prevents the A/C compressor from engaging to protect the system from damage.
Insufficient refrigerant can cause the A/C pressure switch to signal a low-voltage state to prevent compressor burnout.
A failed or malfunctioning pressure sensor may incorrectly report low voltage to the PCM regardless of actual pressure.
Frayed, shorted, or corroded wiring between the A/C request source and the PCM can cause a low voltage reading.
The interior climate control panel may fail to send the proper request signal to the engine computer.
A failure in the PCM's input processing circuit for the A/C request signal.
Not necessarily. This code refers to the electrical request signal; the compressor may be mechanically sound but is simply not receiving the command to turn on.
No. PCM failure is extremely rare for this circuit. You should first check refrigerant levels, the pressure switch, and the wiring harness.
Yes. If a leak causes the refrigerant to drop below a minimum threshold, the pressure switch will trigger a signal that the PCM may interpret as a circuit low condition.