I have hundreds of wasps behind my vinyl siding. I have sprayed with wasp spray. While it kills the ones I can see, by the same night there are more. What can I do to kill the ones behind the vinyl? Is there anything a can spray. There are no nests outside They must be hidden.

Spraying a can of pyrethrum like Clear Zone Pyrethrin Aerosol with a crack and crevice straw (tube) will do a very good job. The straw tube is very small and should get behind the vinyl, killing the wasps.

Sprayed a complete saturation directly into the nest to kill out the whole nest.

For the past 3 or 4 months we have found wasps flying around even though it is winter. Some are out of energy and some full of energy. We have no idea where they are coming from. Any suggestions?

Wasps will crawl in the openings under siding and around plumbing, etc. to over-winter. During periods of warm weather they think it is springtime and try to leave their winter home. They then accidentally come inside. The only long- term solution is to seal and caulk openings from the outside. Recommended products to spray around the entry points during the fall  before the wasps have a chance to over-winter inside would be :
Cyonara 9.7 or Demon WP sprayed in that area.