Get a Vortex II upgrade kit from Amazon. They have single speed or 3 speed with reverse. The 3 speed model is just under $60, a whole lot cheaper than CW, by about $50. I replaced the vent fan I had that didn't do anything with the kit. It took about a 1/2 hour to do it from the inside, maybe 3/4 hour if you don't read the instructions. I got the multispeed fan and it does a great job. Not as noisy and the old on also.
2014 Palomino Puma 25RS
2011 F-150 Super Crew XLT
Days camped in 2014 - 23 Camped 2015 - 47
Camped 2016 - 58 done - 13 more planned so far
2017 - 14 nights reserved