A/C Request A Circuit Low
The P2520 code means the vehicle's onboard diagnostic system has detected: A/C Request A Circuit Low. This is a low severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $80 - $350 (parts and labor)
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Common Symptoms
- A/C compressor won't engage
- A/C button appears to work but no cooling
- Check engine light on
- Climate control display shows A/C active but no cold air
Probable Causes (Ranked by Likelihood)
- Short to ground in A/C request signal wire Very High
- Failed A/C pressure switch holding line low High
- Corroded A/C relay control connector Moderate
- ECM input circuit fault Low
Frequently Asked Questions
What does A/C Request Circuit Low mean?
The voltage on the wire that tells the ECM to turn on the A/C is lower than expected, usually from a short to ground or failed component pulling the signal low.
Could a bad A/C pressure switch cause P2520?
Yes. Some A/C systems route the request signal through a pressure switch. A failed switch can hold the signal low, preventing compressor engagement.
Is P2520 expensive to fix?
Usually not. The most common causes are wiring issues or a failed switch, both relatively inexpensive repairs.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Check A/C request signal voltage at ECM
-
Test A/C request wire for short to ground
-
Inspect A/C relay and related connectors
-
Verify A/C pressure switch allows compressor engagement
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
Commonly Affected Vehicles
- 2010-2020 Toyota Corolla
- 2012-2019 Honda Accord
- 2008-2018 Ford Escape
- 2011-2020 Chevrolet Cruze
Related Codes
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