Powertrain, generic (extended)

P2524 A/C Request B Circuit High

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

P2524 indicates that A/C request input B reads above the level the engine module treats as valid. A line chafed against battery or ignition feed, an open pull-down inside the module or a control unit that latches its output high are the usual explanations. Ford is the one maker found to list it: its 2014 BOSS 302S code list shows P2524 without a lamp mark, just like its A-side counterpart P2521; no thresholds are given. A heavy-duty bulletin from Mack mentions a P252400 on MP10 engines, but in an oil pressure context, so that use is maker-specific and unrelated. CARB A/C monitoring applies only where the request alters fuel or spark control. P2523 is the low side, P2522 the general fault on B. Expect A/C behaving on its own.

Likely causes

Input B wire shorted to battery or ignition voltage
Sending module output latched high
Engine module input stage faulty

Symptoms

  • Compressor engages although not requested
  • A/C cannot be switched off or on as expected

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 bhvac module

Related codes

P2522P2523P2521

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