First, check your fuses. If those are fine, then I'd check your fan diode. Those have gone out before on some people. If the fan isn't working, it'll cause your quad to overheat fairly quickly.
Hey, I had the same problem not too long ago. Check the stuff Sanny told ya and then, if that ain't it, check your wiring. A rat got to mine and chewed up the wiring and two connectors that go to the fan. A trip to Bluestem Farm and Ranch Supply and $6 later, I had the connectors and after about 20minutes of work all was well. :thumbsup:
JD