Why is my Vaillant VAI 3-025 WN Air Conditioner not cooling or heating properly?
- JJennifer LopezJul 31, 2025
If your Vaillant Air Conditioner isn't cooling or heating enough, several factors could be the cause. Check if doors or windows are open and close them. Remove any nearby heat sources, and ensure the thermostat is set correctly. Also, check for obstructions blocking the air inlet or outlet. Wait a few moments to see if the ambient temperature reaches the set level. Clean a dirty or blocked air filter, which should be done every 15 days. Finally, use a curtain to block direct sunlight during cooling.