How to Fix / Troubleshooting

Safety first: Turn off power before deep cleaning.

Steps:

Clean filters: Wash the Bosch filters thoroughly and dry them.
Use coil cleaner: Apply a non-rinse foaming evaporator coil cleaner suitable for AC units to the indoor coil, following product instructions.
Clean drain pan: Wipe the pan with a cloth and a mild disinfectant solution, avoiding electrical components.
Run in Fan mode: After cleaning, run the unit in Fan-only mode for 30–60 minutes to dry the coil and reduce future mold growth.

Persistent odor: Consider professional chemical cleaning of the Bosch indoor unit.

A strong musty or moldy smell occurs when the air conditioner starts.

Possible Causes