How to diagnose and fix a failing heater core in an Audi A2?

I've noticed that my Audi A2's heater isn't functioning properly, with the air blowing out being cold instead of warm. I suspect it may be due to a failing heater core. How can I accurately diagnose the issue and address it before it becomes a major problem?

Firstly, check the coolant levels in your Audi A2 and ensure they are at the correct levels. If they are low, it could indicate a leak in the system. If the levels are fine, then the issue is most likely with the heater core.

To diagnose a failing heater core, check for any signs of coolant leaks or a strong, sweet smell coming from the vents. You can also perform a pressure test on the cooling system to confirm the issue.

If the heater core is indeed failing, it will need to be replaced. This can be a difficult and time-consuming task, so it may be best to seek the help of a professional mechanic. However, if you have the knowledge and tools, you can attempt to replace it yourself.