Growing in vented garage seperate from house

I have a good garage in the back of my house that would be perfect for a few plants. It is brick with screen vents all over at about head level. How will this effect my temperatures. This is in Central Florida area should be from about 50-80 degrees Fahrenheit for about the next three months. I wanted to get one of those new grow tents and put it in there with a fan, carbon filter 400 watt lighthttp://cgi.ebay.com/New-4x4-x-6-5-HYDROPONIC-GROW-TENT-HYDRO-BOX-HUT_W0QQitemZ360092117151QQcmdZViewItem?hash=item360092117151&_trkparms=72%3A1205|39%3A1|66%3A2|65%3A12|240%3A1308&_trksid=p3286.c0.m14

http://cgi.ebay.com/400-watt-HPS-MH-Hydroponic-Grow-Light-400w-Sodium-Lamp_W0QQitemZ160282415666QQcmdZViewItem?hash=item160282415666&_trkparms=72%3A1205|39%3A1|66%3A2|65%3A12|240%3A1309&_trksid=p3286.c0.m14.

I was thinking about getting a small portable ac unit but I'm thinking about how I would regulate it all. Let me know what you think.

you can probably go without the ac until it gets warmer, if your venting is adequate. in the summer a portable ac works great but you do need to vent the heat from the unit.