How to fix a non-functioning heater in Audi A2?

My Audi A2's heater is not working. It only blows cold air no matter what temperature setting I choose. Any advice on how to fix this issue?

First, check the coolant level in your car. Low coolant levels can cause the heater to not work properly. If the coolant level is fine, then it may be a problem with the heater core. You may need to replace it.

Have you checked the heater blower motor? It may be worn out or malfunctioning, causing the heater to not work. Consider replacing the blower motor if necessary.

The issue may be with the thermostat. If it's stuck in the open position, it could prevent the heater from working. Have it inspected and replaced if needed.