A/C Request Circuit Low
The P2520 code indicates that the Powertrain Control Module (PCM) has detected a low voltage condition on the A/C request circuit. This circuit carries the signal from the A/C control head to the PCM, which then engages the A/C compressor clutch. A low voltage reading suggests a short to ground, open circuit, or faulty component in the signal path, preventing the A/C system from activating.
01. Most Common Causes
- Faulty A/C pressure sensor
- Short to ground in A/C request circuit wiring
- Open circuit in A/C request circuit
- Faulty A/C control module or head unit
- Corroded or damaged connector at PCM or A/C components
02. Symptoms You Will Notice
- A/C compressor does not engage
- No cold air from vents
- A/C system inoperative
- Check Engine Light illuminated
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to verify the code and check for related codes.
Step 2: Inspect the A/C request circuit wiring and connectors for damage, corrosion, or shorts.
Step 3: Test the A/C pressure sensor signal voltage with a multimeter; compare to specifications.
Step 4: Check the A/C control module output signal to the PCM.
Step 5: If all else is normal, suspect a faulty PCM and perform further diagnostics.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, it is safe to drive, but the A/C will not work. The vehicle's engine and drivetrain are not affected.
How much does it cost to fix?▼
Typical repair costs range from $50 to $150 for diagnosis and repair, depending on the root cause and labor rates.