washed the engine bay a bit sat....now heat blows cold?

[jasonroman]

make any sense?
sat after work, i decided to try and clean up the engine a little bit and change my valve cover gaskets.
so i sprayed a little simple green and then water to try and get some of grime and grease off.
then i hit it with a little compressed air. changed valve cover gaskets.
then monday was taking my son to school and noticed that cold air was blowing.
why would this happen?
prior to wash and gaskets, the heat worked as it should.??