Why is the radiator in my Audi 80 not working properly?

I noticed that the radiator in my Audi 80 is not producing enough heat despite the engine running normally. What could be causing this issue and how can I fix it?

The most likely cause of this issue is a faulty or clogged radiator. It is important to have it checked and replaced if necessary by a professional mechanic to prevent damage to the engine.

Another possibility is a malfunctioning thermostat which regulates the temperature of the engine. It is recommended to have it replaced by a certified mechanic.