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P2519

A/C Request A Circuit

General electrical fault on the A/C compressor request input A. This input tells the ECM that the HVAC controller wants the A/C compressor engaged. With the input invalid, the ECM cannot enable the compressor clutch — A/C does not cool, idle-up compensation is not applied.

  • Check engine light: Yes
  • Emissions related: No
  • Repair difficulty: medium

Common causes

Ordered by how often each turns out to be the cause.

  • Open or shorted A/C request wireCommon
  • HVAC module not transmitting the requestPossible

Parts involved

  • AC Request Input A
  • Hvac Module

P2519 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.