why does my BMW 3 Series G20/G21 (2019-2024) have a weird smell when I turn on the AC?

Solution

1. Preparation

• Tools Required: Socket set, screwdriver set, vacuum cleaner, disinfectant spray
• Disconnect the vehicle's battery to prevent electrical issues while working.

2. Replace Cabin Air Filter

• Locate the cabin air filter housing (usually behind the glove box).
• Open the glove box and remove any obstructing components.
• Unscrew and remove the cabin air filter cover.
• Take out the old cabin air filter and inspect for mold or debris.
• Insert a new cabin air filter (ensure it’s the correct type for the G20/G21).
• Reassemble the cover and glove box components.

3. Clean the Evaporator Core

• Remove the dashboard panel if necessary to access the evaporator core.
• Use a vacuum cleaner to remove any debris and dust from the evaporator.
• Spray a disinfectant cleaner specifically designed for HVAC systems on the evaporator core to eliminate mold and bacteria.
• Allow the cleaner to sit for the recommended time before wiping it off gently.

4. Clear the Drain Tube

• Locate the AC drain tube, typically found under the vehicle on the passenger side.
• Check for obstructions or clogs in the drain tube.
• Use compressed air or a flexible cleaning brush to clear any blockages.
• Ensure that water flows freely from the drain tube when the AC is running.

5. Reassemble and Test

• Reattach any panels or components removed during the process.
• Reconnect the battery and start the vehicle.
• Turn on the AC system and monitor for any odors.
• Test the airflow and temperature settings to ensure proper operation.