Fan not running.

First off, thanks for the help. I have a fridigaire all fridge that I keep in my garage for beer purposes. A week ago I noticed that to top of the fridge was quite warm and the bottom cold. The compressor was running but I couldn't hear the fan. After reading a bunch of post here and on other sites I figured the fan was bad and went out and bought a new one. No dice. I replaced the fan and it still wouldn't spin. I dug a little deeper and read about testing voltage at the plug. With the fridge plugged in the compressor running I only seem to be getting about 20v at the fan plug. Now I'm lost, any ideas what to check next?

Thanks,

Mark.