Yes, but if using a modern compressor fridge like a Dometic or Isotherm that uses either a BD35F or BD50F Danfoss compressor *and* tapping off the fridge's wiring, make sure to not exceed the fan output's rating of .5A sustained or 1A burst for 2 seconds or the compressor will turn off as per the the attached document in this
link.
I can't help but wonder if folks are not seeing reduced duty cycles on the fridge because the combo of the stock fan and a second or even a third is causing the fault to shut off the compressor and likely the fans with it in a "Fan Over-current Cut-out". I'm a bit surprised folks are not contacting the manufacturer of the fridge before hooking a fan up to the fridge's wiring, that is what I did and they sent me the tech manual in PDF.