Code result
P2521
A/C Request A Circuit High
Moderate severity
What it means
The A/C request input A reads stuck high — typically a short to battery voltage. The ECM cannot pull the line low to read switch state, so the A/C compressor request is treated as invalid and the clutch stays disengaged.
Is it safe to drive?
Use caution
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
Request wire shorted to battery voltage
highOne of the most commonly reported causes for this code — check this first.
Connector pins corroded - high contact resistance
lowLess common, but worth ruling out after the more likely causes.
Supply wire pinched against B+ source
lowLess common, but worth ruling out after the more likely causes.
Related help
Get the full diagnosis
Add your vehicle and see step-by-step repair help, recalls, and TSBs in Wrenchify.
Diagnose P2521 freeNo credit card required