Condensation on inside of Lexus 330
I'm getting condensation build up on the inside of my Lexus 330 when parked
overnight. All windows are closed tightly. It is particularly heavy on the
windshield and rear window.
Interior moisture will condense on cooler surfaces as your car sits overnight. To reduce this moisture, run your A/C to dehumidify the interior air of the car before parking it. And, of course, keep windows rolled up to keep dampness out. If you still have some foggy windows in the morning, run the A/C again to defrost things. You might want to check inside your trunk under the spare tire. Sometimes water will accumulate there and raise the interior dampness that causes this problem.
I did have moisture under the passenger side rear floor mat one time recently. After drying it out, I have attempted to find if there is a leak by using hose and hosing the car down and I've also let it sit outside overnight in the rain, but the rear floor mat remained dry.
Buy a chemical dehumidifier to suck excess moisture out of your car. If there is no leak you can dry the interior out this way but don't let it tip over.