A/C Request Circuit Low
The P2520 code indicates that the Powertrain Control Module (PCM) has detected a low voltage condition in the A/C request circuit. This circuit carries the signal from the A/C control head to the PCM, requesting compressor engagement. A low voltage reading suggests a short to ground, open circuit, or faulty component, preventing the A/C system from activating.
1. Most Common Causes
- Short to ground in the A/C request circuit wiring
- Excessive resistance or loose connection in circuit connectors
- Faulty A/C request switch
- Internal failure of the HVAC control module
- Faulty A/C compressor relay
- Internal PCM failure (less common)
2. Symptoms You Will Notice
- A/C compressor does not engage
- No cold air from vents
- A/C indicator light may not illuminate
- Possible check engine light on
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and check freeze frame data.
Step 2: Visually inspect A/C request circuit wiring and connectors for damage or corrosion.
Step 3: Using a multimeter, check for voltage at the A/C request signal wire at the PCM connector with A/C on (should be near battery voltage).
Step 4: Test A/C pressure switch and A/C control head for proper operation per service manual.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, it is safe to drive, but the A/C will not work. Driving without A/C may cause discomfort but does not affect engine or safety systems.
How much does it cost to fix?▼
Typical repair costs range from $50 to $150 for diagnosis and repair, depending on the root cause (e.g., wiring repair vs. component replacement).
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.