What Does P2520 Mean?
The PCM has detected a low voltage signal on the A/C request circuit 'A'. This circuit carries the signal from the A/C controls to inform the PCM that air conditioning has been requested by the operator.
Common Causes
35%
Short to ground in A/C request signal wire
30%
Faulty A/C control head or switch
20%
Damaged or corroded connector at A/C control module
15%
Failed PCM internal pull-up circuit
Diagnostic Steps
1
Step 1: Inspect A/C control module connectors and wiring for visible damage, corrosion, or moisture
2
Step 2: Measure voltage on A/C request circuit at PCM connector with A/C off; should read approximately 5V or 12V depending on system design
3
Step 3: Disconnect A/C control module and check for short to ground on signal wire; should read open circuit
4
Step 4: With A/C control disconnected, apply appropriate reference voltage to signal wire and verify PCM recognizes signal change
5
Step 5: Test A/C control module operation using manufacturer-specific diagnostic procedures or substitute known-good module
Estimated Repair Cost
$100 - $500
Parts + labor, varies by vehicle and location
The PCM has detected a low voltage signal on the A/C request circuit 'A'. This circuit carries the signal from the A/C controls to inform the PCM that air conditioning has been requested by the operator.
The most common cause of P2520 (A/C Request "A" Circuit Low) is: Short to ground in A/C request signal wire
Typical repair costs for P2520 range from $100 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
No direct safety concerns; air conditioning system may not function properly, reducing driver comfort and potentially affecting defroster operation.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2520 to identify the root cause.
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Quick Info
Category
Powertrain
System
Climate Control System
Difficulty
Type
Generic (SAE)
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