Powertrain, generic (extended)

P2519 A/C Request A Circuit

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P2519 covers the general circuit fault of a wired input through which the climate control asks the engine module for compressor operation. The engine module needs this request early, to raise idle speed, add torque reserve and then energise the compressor clutch relay. CARB therefore demands monitoring of electronic A/C components wherever switching the A/C changes fuel or ignition control, phased in from 2006 to 2008. Many current cars carry the request over CAN instead – Saab's 2011 9-5 is an example, with the HVAC module sending it as a message – and then network faults appear as U-codes rather than P2519. No maker documents P2519 publicly. P2520 and P2521 name a low or high level on the same input, P2522 the second input B. Expect A/C that does not start.

Likely causes

Request wire broken or connector loose
Climate control unit or A/C switch not sending a valid signal
Engine module input stage faulty

Symptoms

  • A/C compressor never engages
  • Idle speed does not rise when A/C is selected

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–400
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

ac request input ahvac module

Related codes

P2520P2521P2522P0645

References: law.cornell.edu, saabwisonline.com.