Alright so my exhaust fan was working fine pushing enough air out to keep my box in the temps where i wanted them. But then later today the fan stopped working correctly and only pushes a minimum amount of air out and my box temp is 104 F
Are you using a fan speed controller or is it wired direct? If it's wired direct then you should look at getting a replacement. Sucks, but shits made cheap now-a-days.
What's your intake situation? Is there a window or duct that used to be open and is now closed? If there's no way for new air to get in then that could also reduce the effectiveness of your exhaust fan and raise your temps.