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P2519 — Ac Request Circuit

Manufacturer-specificPowertrain (engine & transmission)

The P2519 code indicates a fault in the A/C request circuit, which is the electrical signal that informs the engine control module (PCM) that the air conditioning has been requested. When the PCM detects an open or short circuit in this line, it will prevent the A/C compressor from engaging to protect the system.

Symptoms

What causes it — most likely first

1. Wiring Harness Damage

Frayed, broken, or shorted wires between the HVAC control head and the PCM.

2. Faulty HVAC Control Module

Internal failure of the climate control head or switch preventing the request signal from being sent.

3. Corroded Connectors

Moisture or oxidation at the electrical connectors causing high resistance or a complete break in the circuit.

4. Defective Pressure Switch

A malfunctioning A/C pressure switch that incorrectly interrupts the request circuit.

5. PCM Internal Failure

An internal circuit failure within the engine control module preventing the signal from being processed.

How it's diagnosed

  1. Verify the A/C system has an adequate refrigerant charge to ensure pressure switches are closed.
  2. Inspect the wiring harness for visible signs of chafing, melting, or rodent damage.
  3. Test for continuity and voltage on the A/C request circuit using a digital multimeter.
  4. Inspect all electrical connectors for corrosion or loose pins.
  5. Use a scan tool to monitor the A/C request status while toggling the HVAC controls.
  6. Perform a pin-out test at the PCM to determine if the request signal is reaching the module.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationManufacturer-specific (P1/B1/C1/U1)
Related codesP2510 — Ecmpcm Power Relay Sense Circuit RangeP2511 — Ecmpcm Power Relay Sense Circuit InterP2512 — Event Data Recorder Request Circuit OpP2513 — Event Data Recorder Request Circuit LoP2514 — Event Data Recorder Request Circuit HiP2515 — Ac Refrigerant Pressure Sensor B Circu

Frequently asked

Does this code mean my A/C compressor is mechanically broken?

Not necessarily. P2519 is an electrical circuit code; the compressor may be perfectly functional but is simply not receiving the command to turn on.

Can a blown fuse trigger this code?

Yes, if the HVAC control head or the circuit providing power to the request signal is unprotected by a blown fuse.

Should I replace the PCM to fix this code?

No. Replacing the PCM is rarely the solution for P2519. The vast majority of cases are caused by wiring issues or faulty HVAC control switches.