HVAC Blower Relay Circuit Malfunction
The B2515 code indicates that the control module has detected a fault in the HVAC blower relay circuit. This can be caused by a short to ground, a short to battery voltage (B+), an open circuit, or an internal failure of the blower relay. Since the relay controls power or the control signal to the blower motor, this DTC can result in the blower being completely inoperative, directly affecting cabin climate control and windshield defrosting capability.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty HVAC blower relay with burned or damaged internal contacts
- Short to ground or to battery voltage (B+) in the relay control or power circuit wiring
- Open circuit or excessive resistance in the relay circuit wires or connectors
- Corroded, retracted, loose, or damaged pins in the relay connector
- Internal failure of the HVAC control module or front control module (FEM) that commands the relay circuit
3. Symptoms You Will Notice
- Blower motor does not operate at any speed
- Inability to defrost windshield or control cabin temperature
4. Step-by-Step Diagnosis
Check for blown fuses related to the blower motor circuit and replace if necessary.
Inspect the blower relay for signs of damage, corrosion, or burnt contacts; test relay operation with a multimeter.
Verify voltage and ground at the relay coil and switch terminals using a wiring diagram.
Check for shorts or opens in the wiring between the relay, control module, and blower motor.
If wiring and relay are okay, test the HVAC control module or FEM for proper output signals.
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, but without HVAC blower operation, you may lose defrosting capability, which can be a safety hazard in foggy or cold conditions. It's best to repair promptly.
How much does it cost to fix?▼
Typically $100 to $300, depending on whether the relay, wiring repair, or control module replacement is needed.