Why is the car heater not hot?

The reason for this is the following：

1. The heater switch of the vehicle is faulty;

2. The air conditioner filter is too dirty to let the air out;

3. The heater is out of order; 4. The engine thermostat is damaged;

5. Lack of antifreeze;

6. The antifreeze needs to be replaced during the replacement cycle;

7. The vehicle antifreeze circulation pipeline is blocked.