Foggy windows, whether outside or inside, occur for one reason: different temperatures in the cabin and ambient air. If you live in a cold climate area, you will often stay in the car with a heater. And if you’re driving on a hot, sunny afternoon, you need air conditioning to keep you cool inside the cab.
When using a car heater or air conditioner to keep cool, the outdoor and indoor temperatures are not the same. This will invariably fog up the car windows. Using an air conditioner can cause the windows to fog up from the outside, while using a car heater will cause the windows to fog up from the inside.
In this article, you will learn what causes car windows to fog up inside when parked and what to do in such situations.
What causes car windows to fog up on the inside when parked?
As explained above, condensation occurs due to changes in temperature. This does not matter if you are driving or parked. Let’s narrow things down to see why car windows fog up in winter, whether you’re driving or parked.
passengers exhaling
If the passengers are inside the car, nothing will prevent them from exhaling, whether they are asleep or awake. The air they exhale will turn to condensation once it touches the windows and the outside temperature is well below cabin temperature. Condensation will fog up your car from the inside.
Rain
Having the car windows fogged up on the inside when it rains is normal. If you park your car in an open space and it rains, the ambient temperature will be much lower than the cabin temperature. Due to the temperature difference, the car will fog up from the inside.
Using the car heater
If you park your vehicle in a cold area where the interior cabin is cold, you’ll likely turn on your car’s heater if you have one. While turning up the car’s heat will keep you warm and comfortable, it will increase the cabin temperature and cause the windows to fog up from the inside.
sweat or heat
If the passengers and the driver sweat inside the car, their body heat will condense when it reaches the windows. Condensation will cause the windows to fog up and fog up.
Now that you’ve seen what causes fogging inside car windows, let’s take a look at how to prevent car windows from fogging up inside.
What to do if my car windows fog up inside when parked?
Depending on the root cause, windows fogging up from the inside means that the interior temperature is higher than the ambient temperature. In order to prevent the car windows from fogging up in the morning when it is parked, you need to make sure that the ambient temperature and the cabin temperature are the same.
Here’s what to do if your windows fog up on the inside when you’re parked;
break the windows
If you want to sleep in the car, open the windows to allow outside air into the cabin. This way, your breath will not reach a dew point when it hits the glass. The dew point is when condensation touches the windows and the outside temperature is well below cabin temperature.
Alternatively, you can turn on the air conditioning if you don’t want to break the windows. But please don’t leave the engine and air conditioning running while you sleep. It is not safe to sleep in a car with the engine running. Sleeping in the car with the engine running will allow exhaust gases that contain carbon monoxide to enter the cabin.
Park your vehicle in a garage
Always park your vehicle in the garage when it is raining. Leaving the vehicle in an open space when it is raining will cause it to fog up on the inside. To prevent this from happening, park the vehicle under shade.
Turn off the car heater.
If the vehicle fogs up from the inside when using the car heater, open the windows or turn on the air conditioning. This will allow the ambient and cabin air temperatures to remain at the same rate. However, remember to turn off the air conditioning once the interior fog has cleared. Otherwise, the windows will start to fog up from the outside.
Check out this comprehensive article explaining how to stay warm in a car with no heater. Staying warm in an unheated car will prevent your car from fogging up on the inside.
For a more comfortable solution, turn on the car’s defroster and blow warm air across the windshield and windows to remove any moisture buildup on the windows. Check if your vehicle’s climate control system has a recirculation function and turn it off. If the system is on, the vehicle’s air conditioning or heating reuses air from inside the vehicle instead of drawing air from the environment.
You want your car to drag the ambient car into the car to prevent your breath from fogging up the car from the inside. This explains why you should disable the recirculation feature. If you don’t know if your car has this recirculation feature, look for a button on the dash with a circular or semi-circular arrow. In order not to escape, some vehicles will have an icon of a car with a circle inside.
Frequently Asked Questions – Frequently Asked Questions
Why do my car windows fog up on the inside at night?
Generally, cars parked in open spaces fog up overnight as the temperature inside the cabin is higher than the ambient temperature.
This is what is happening. At night, condensation occurs due to the difference in outdoor and indoor temperatures. As warm cabin air and cool ambient air strike the windows simultaneously, the temperature difference coats the windows with condensation.
How do I prevent my car from fogging up on the inside?
Car fogging from the inside or outside is not unusual, although it can be annoying at times. However, there are smart ways to prevent your car from fogging up at night. These include using a silica dehumidifier, applying an anti-fog coating, and disabling the recirculation feature when using air conditioning and car heaters.
Is it normal for car windows to have condensation on the inside?
It is absolutely normal for car windows to condense on the inside. So don’t worry when it happens to your car windows. As already mentioned, condensation occurs due to changes in cabin temperature and ambient temperature. However, you can prevent or stop it by following the steps in this article.
Should I worry about condensation on the windows?
You don’t have to worry if your car condenses when it’s parked. All you have to do is wipe off the fog with a clean rag and open the windows. On the other hand, you should be concerned if it happens while driving because it can impair your eyesight, invariably increasing the risk of accidents on the road. If you want to use your heater in cold weather, set the temperature to maximum and turn on the air conditioner to dry out any moisture.
Is it hot or cold to demist the windows?
Heat is often better than cold for defrosting windows. According to Road and Track, the best way to defog your car is to turn the heater on full, then turn on the air conditioning. This way, the heat will hold more moisture, while the air conditioner will pull moisture from the air as it passes through the cooling coils.
What can I spray on the windows so they don’t fog up?
While fogging is normal, in most cases it is very disconcerting and frustrating. For this reason, drivers often look for what to spray on the windshield and windows to discourage fogging. If you don’t want your windows to fog up from the inside, clean them thoroughly with a soft towel and apply anti-fog spray. Apply the same step on the outside glass if you don’t want your windows to fog up from the outside.
How much does it cost to repair condensation on windows?
Repairing car window condensation doesn’t cost a fortune, depending on the root cause. In most cases, all you need to do is turn on the car’s heater to the maximum setting and also turn on the car’s air conditioner. In other cases, you may need to use a dehumidifier to clean to prevent windows from fogging up. However, if your window heat seals are damaged, you may need to spend $100-$200 to repair it.
to finish
Car windows fogging up on the inside when parked is normal. However, it can be frustrating and bewildering at times. Here at Mechanic Rx, we don’t want you to get frustrated. That is why this article has answered the question, why do my car windows fog up awhen parked and described
what to do in such a situation? It also suggests preventative measures and their implementation can help you avoid the hassle. But if you fall victim to this unnecessary situation, follow the guidelines to the letter to successfully defog your car windows.
