Right in front of the battery there is a liitle white cap that has an "H" on it.
I noticed that mine is not there and there seems to be some sort of pressure valve there, what is this cap and will I have problems with mine being missing?

 

cooling system cap, or the radiator cap.
you better get one before you drive it again.

 

A wild guess because I'd have to look at my car.

Only H know of could be the high pressure line for thwe A/C

 

It is the size of a dime approx. Its to the left of the radiator cap. I was thinking it was maybe the secondary air control valve??? I dont know how long Ive been without one, but was curious if any one knew if the cap was instrumental in the function of the valve or just a cover?

 

It's the High pressure line tap connection for the A/C system, the A/C pressure switch is also in the same area, if you unscrew the protective cap you'll see the valve stem underneath, leave it alone unless you want to lose the freon refrigerant out of your A/C system ....

edit: see that yours is missing, recommend replacing it, you need to keep the valve stem area clean to avoid getting contaminants into the A/C system when it gets worked on/used

 

Thanks TeamRX8