
The most effective way to eliminate condensation inside your car is to run the air conditioning with the fresh air setting turned off. This works because the A/C system acts as a dehumidifier, pulling moisture from the air as it cools it. Combine this with turning on your windshield defroster, which directs dry, warm air onto the glass to accelerate evaporation.
Condensation forms when warm, moist air inside the car hits a cold surface, like the windshield, reaching the dew point. To fix it, you need to either raise the temperature of the glass or lower the moisture level in the air.
Immediate Action Plan:
For a long-term solution, you must address the source of the excess moisture. Common causes include wet floor mats, a clogged cabin air filter, or a small water leak from a damaged door seal or blocked sunroof drain. Check and dry out your floor mats regularly and inspect door seals for cracks.
| Common Cause of Moisture | DIY Check/Fix | Estimated Cost if Professional Repair is Needed |
|---|---|---|
| Wet Floor Mats/Clothing | Remove and dry thoroughly. | $0 |
| Clogged Cabin Air Filter | Replace filter (usually behind glovebox). | $15 - $50 (part only) |
| Faulty Door Seal | Inspect rubber seals for tears or gaps. | $100 - $300 per door |
| Blocked Sunroof Drain | Locate drain tubes and clear with compressed air. | $150 - $250 |
| Heater Core Leak (Rare) | Sweet smell, film on windshield; requires mechanic. | $1,000 - $1,500 |
Persistent condensation, especially on the inside of all windows, is a sign of a significant humidity problem. If the quick fixes don't work, you likely have a leak that needs to be found and sealed by an auto technician.

My old truck used to fog up like crazy every morning. My cheap fix? A sock filled with cat litter. No joke. Just fill a sock with silica gel crystal cat litter (the stuff that clumps), tie it off, and toss it under a seat. It soaks up the damp air overnight. During the day, always run your A/C with the heat on defrost. It’s the fastest way to clear the glass and keep it clear. Works better than just wiping it with a cloth.

This is almost always a humidity issue. Your goal is to balance the interior air temperature with the outside to prevent reaching the dew point. The most efficient method is to use your climate control system correctly. Turn off air recirculation to stop adding moisture from your own breath. Then, activate the defroster with the A/C on. The A/C compressor removes humidity, while the heat dries the windshield. A clean cabin air filter is essential for this system to work effectively.

First, check for simple culprits. Are your floor mats soaked? Is there a wet umbrella or gym bag in the back? Get that moisture out. Then, for a quick clear-up, turn your defroster to full blast, hit the A/C button, and make sure the recirculated air setting is OFF. This pulls in drier outside air. If fogging happens often, you might have a leaky door seal. Feel along the bottom of the door seals for dampness after rain. A small leak can let in a lot of water over time.


