Cause of Condensation:
The cause of most condensation problems is fairly well-known, and basically every single aftermarket headlight or taillight out there on the market can potentially suffer from some amount of fogging or condensation. The root cause is the the pressure equalization vents that are built into each light. These vents exist so that the lights can be used in various climates and altitudes without causing pressure issues that could cause seal or lens failures. However, the vents are also an ingress point for moisture, though typically condensation and fogging from the pressure equalization vents is usually extremely minimal and only occurs due to large swings in temperature and humidity over a short time period.
Another possible cause of moisture and condensation build-up is loose bulbs seals or the addition of aftermarket HID or LED conversion kits that make it so you're unable to reuse the bulb housing covers or other seals. The actual bulb fittings and cradles on most aftermarket headlights and taillights aren't what actually seal the housing off. Usually the dust covers or bulb housing seals are what help keep moisture, dust, grime, you name it out of your headlights or taillights of choice. If those dust covers and seals aren't fully secured around the bulb housing, or if you're running a conversion kit that makes it so you can 't use the dust covers, you could very easily have problems with condensation.
There are a few ways you can at least limit the chances of condensation with your aftermarket headlights and taillights. First and foremost, make sure all dust covers and seals are complete secured on your lights. Also double-check any applied silicone for wiring for cracks, fissures, and general wear and tear. If you're running an aftermarket HID or LED conversion kit, try to come up with your own dust covers or bulb housing seals. To help prevent moisture buildup from the vent tube, try to keep your vehicle in a garage or other cool, dry place. We know that's not always possible, so just do what you can.
Most of the aftermarket taillight and headlight manufacturers that we carry are pretty willing to help you out, if your headlights or taillights do have severe condensation issues. ANZO, Spyder Auto, and Xtune will cover condensation problems for the entirety of their 1-Year Limited Warranty (though ANZO does require the end user to pay shipping back after 30 days). Recon covers severe condensation problems for the term of their 90-day limited warranty. If you have any further questions about condensation-related problems or issues, feel free to give us a call directly at 1-877-578-2433.