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P2522 — Ac Request B Circuit

Manufacturer-specificPowertrain (engine & transmission)

OBD-II code P2522 indicates a problem with the Air Conditioning (A/C) Request B Circuit, which is responsible for signaling the engine control module (PCM/ECM) to engage the A/C compressor. This code typically means the PCM has detected an electrical fault, such as an open or short, in the circuit that controls the A/C request signal.

Symptoms

What causes it — most likely first

1. Faulty A/C pressure switch or sensor

The A/C pressure switch or sensor may be defective, sending incorrect signals or no signal to the PCM, causing the circuit to fail.

2. Damaged or corroded wiring or connectors

Wiring or connectors in the A/C Request B Circuit may be frayed, broken, or corroded, leading to an open or short circuit.

3. Blown fuse or faulty relay

A blown fuse or defective A/C relay in the circuit can prevent the signal from reaching the PCM, triggering the code.

4. Faulty A/C control module or climate control panel

The A/C control module or climate control panel may be malfunctioning, failing to send the proper request signal to the PCM.

5. Defective A/C compressor clutch or coil

The A/C compressor clutch or its coil may be faulty, preventing engagement even when the signal is present.

6. PCM/ECM software or hardware issue (rare)

While uncommon, a fault in the PCM/ECM software or hardware could incorrectly interpret the A/C request signal, though this is a last-resort diagnosis.

How it's diagnosed

  1. Inspect the A/C pressure switch and sensor for proper operation using a scan tool or multimeter to verify signal output.
  2. Check the A/C Request B Circuit wiring and connectors for damage, corrosion, or loose connections. Repair or replace as needed.
  3. Test the A/C relay and fuse for continuity and proper operation. Replace if defective.
  4. Verify the A/C control module or climate control panel is sending the correct request signal to the PCM using a scan tool.
  5. Inspect the A/C compressor clutch and coil for proper engagement and resistance. Replace if faulty.
  6. If all other components test normal, perform a PCM/ECM software update or consult manufacturer-specific diagnostic procedures for further testing.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationManufacturer-specific (P1/B1/C1/U1)
Related codesP2520 — Ac Request Circuit LowP2521 — Ac Request Circuit HighP2523 — Ac Request B Circuit LowP2524 — Ac Request B Circuit HighP2525 — Vacuum Reservoir Pressure Sensor CircuP2526 — Vacuum Reservoir Pressure Sensor Circu

Frequently asked

Is the PCM/ECM usually the cause of P2522?

No, the PCM/ECM is rarely the cause of P2522. This code is almost always triggered by a fault in the A/C request circuit, such as a bad switch, wiring issue, or relay. Replacing the PCM/ECM should only be considered after all other components have been thoroughly tested and ruled out.

Can I drive with P2522?

Yes, you can drive with P2522, but your A/C system will not function properly. Prolonged driving without addressing the issue may lead to further electrical problems or discomfort due to lack of cooling.

Why does my A/C work intermittently with this code?

Intermittent A/C operation with P2522 is often caused by a loose or corroded connection in the A/C Request B Circuit. The signal may occasionally reach the PCM, allowing the A/C to engage temporarily before failing again.

Do I need a scan tool to diagnose P2522?

While a scan tool can help verify the code and monitor live data, basic diagnosis (such as checking fuses, relays, and wiring) can be done with a multimeter and visual inspection. However, a scan tool is recommended for advanced testing of sensors and modules.