The causes of the fog on windshield –
It’s most dangerous to driving without being able to see because of the fog on the windshield. It happens mostly in winter, it also on rainy day of summer. The cause is the temperature difference between inside the car and the outside.
How to defog your car windshield?
1. Crack open the windows.
Allow fresh air into the car by cracking the windows open. The circulation of outer air alone will often be enough to defog the windshield without the heater/air conditioner. This might not be possible sometimes due to cold or rain, but installing vent visors on the windows can reduce problems like rain.
2. Clean the windshield with towels.
It’s very effective and simple. But it may cause dangerous when driving.
3. Defogging with air condition.
If your car is equipped with automatic air conditioning, you only need to turn on the windshield switch.
If your car is equipped with manual air conditioning
Step 1: Adjust Wind Direction Switch to windshield position ( 
or ) with A/C on.
Step2: Switch on the air-conditioner in fresh air mode ( or off)
4. Defogging Rear Windshield.
Also see – Precautions during winter in Hills
