Wow............lotta bad advice in here.
Yer issues are heat related,ya got plenty of light.
Ya gotta get the heat outta the closet,I like to cut a hole in the ceiling and run the exhaust duct up and out.
I use a 440 cfm inline eco fan with sealed hoods for 1000's,otherwise ya get what yer getting or werser.
I can take some pics of my setup if you want a visual aid.