Take a look on the roof and see exactly what it is (if you don't have the owners manual. I would recommend and exact replacement so you don't have to do anything but unscrew 4 bolts, swap the wiring and screw it back in place. If you are at all handy and have a way to get the VERY heavy unit on the roof it is a do-it-yourself replacement.
What I post is my 2 cents and nothing more. Please don't read anything into my post that's not there. If you disagree, that's OK.
Can't we all just get along?