My Xbox fan is not working right?

Midway through '09, my Xbox got the E74 error. I got it fixed in... November, I think. Ever since then, if I play an open world game, or any other game that takes up a lot of processing power, my Xbox expels some SERIOUSLY hot air out of the fan grating in the back, and then overheats shortly thereafter. I can't help but think it has something to do with the fan. What should I do?