why is my BMW 3 Series AC blowing warm air instead of cold

Solution

1. Preparation

• Tools Required: OBD-II scanner, manifold gauge set, basic socket set, screwdriver set, refrigerant (if needed).
• Ensure the vehicle is parked on a level surface and the engine is off.
• Disconnect the battery to prevent electrical shorts.

2. Inspect and Replace Fuses

• Locate the fuse box (refer to the owner's manual for the exact location).
• Remove the cover and check the AC-related fuses.
• Replace any blown fuses with the same amperage rating.

3. Recharge Refrigerant

• Connect the manifold gauge set to the low and high-pressure service ports.
• Start the engine and turn on the AC to the maximum setting.
• Check the pressure readings; if low, add the appropriate refrigerant until proper levels are achieved (consult specifications for your specific model).

4. Test and Replace AC Compressor

• If the AC compressor is not engaging, check the electrical connections and relay.
• If necessary, remove the AC compressor by:
  • Disconnecting the electrical connector.
  • Removing the serpentine belt.
  • Unscrewing the mounting bolts and removing the compressor.
• Install a new compressor by reversing the removal steps.

5. Replace Cabin Air Filter

• Locate the cabin air filter compartment (typically under the dashboard or behind the glove box).
• Remove the old filter and install a new one, ensuring proper orientation for airflow.