HVAC Compressor Overtemp Protection Active
The B2518 code indicates that the HVAC control module has detected an overtemperature condition in the A/C compressor, typically via the compressor temperature sensor or system protection logic. When the temperature exceeds calibration limits, the module disengages the compressor clutch to prevent internal mechanical damage. This condition may be intermittent or continuous, and the system will remain locked until normal operating parameters are restored.
1. Commonly Affected Makes
2. Most Common Causes
- Low refrigerant level or A/C system leak
- Faulty compressor temperature sensor or open circuit in its wiring
- Failed A/C compressor clutch or coil
- Inoperative condenser fan or blown fan resistor
- Restriction in the refrigeration circuit (expansion valve, receiver-drier)
- Damaged wiring or corroded connectors in the temperature sensor circuit
- Internal mechanical failure of the compressor due to excessive friction
- HVAC control module (FCIM) internal fault or incorrect calibration
3. Symptoms You Will Notice
- A/C compressor clutch does not engage
- Intermittent or no cooling from A/C system
4. Step-by-Step Diagnosis
Check refrigerant pressure and inspect for leaks
Test compressor temperature sensor resistance and wiring continuity
Verify compressor clutch operation and coil resistance
Inspect condenser fan operation and circuit
Check for restrictions in A/C lines and components
Scan HVAC module for additional codes and perform functional test
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive, but the A/C will not cool. Continued driving with an overheating compressor could cause internal damage, so it's best to diagnose and repair promptly.
How much does it cost to fix?▼
Repair costs vary widely depending on the root cause, typically ranging from $150 for a sensor replacement to $1,200 or more for a compressor replacement.