front headlight assembly

In most cases, you would have to replace the lamp assembly. You may want to check with a Chevy dealership to see if they service them also with a seal kit. 99% of the time, though, you are going to need to replace it. As a temporary measure, if you are getting moisture and water to build up inside the lamp assembly, I have seen folks use a tiny drill bit to put a small hole in the bottom of the assembly, allowing moisture/water to escape. More the liquid form rather than vapor, but worth a try anyway.