Refrigerator freezes over

A fan to circulate the air helps even out the cooling in the food section of fridge.

Cooling fins icing over.......
Bad thermistor causing excessive cooling
Bad door gaskets allowing warm air into food section
Placing hot food directly into food section
Warm air getting sucked into food section via drip pan drain

What Brand/Model of fridge?

Besides the fan you might want to check your seal and make sure that you have resisteance pulling a dollar bill out.

There is a clip inside your fridge on the cooling fins that you can move up or down that regulates the temp. Check where yours is set at. Sometimes just moving it a bit lower will fix the problem.

This is just a quick fix as the colder or warmer a thermistor gets is how it works. To check if the thermistor is working properly or at all you have to follow it back to the the other end.

This link explains it more thoroughly.
http://www.ehow.com/how_5671704_check-thermistor-rv-refrigerator.html

Start by checking that the restrictor is still in the condensate drain hose.

Good to have a loop in it (like a P trap) or have the end of it underwater in the drain tray.

If just open, hot/humid air rises into the refrigerator.

Next, as suggested, do the $bill test on the door gasket.

koda55 wrote:
Besides the fan you might want to check your seal and make sure that you have resistance pulling a dollar bill out.

After installing a computer fan that I had laying around I was still getting some frost on the fins. I did the dollar bill test and noticed the bill slipped out easily in several locations. I removed the door latch and filed about .050 of the mounting surface which caused the door to seal tighter. This reduced the frosting that I was getting on the fins.

If it's a Dometic, I think that a board failure will put the fridge into "constant cool" mode...check the documentation.

Really need more info in order for folks to be not just guessing...

Jim

Most fridges are not frost free.. If humidity is high, they ice quickly.

I spent almost 1,000 for new boards and I still get ice.

It's the nature of the beast with an RV fridge. Hot sun on it's backside and everyone opening and closing it more in a day than a home fridge. And the fact of the habit of leaving it open when you get something out and put it on the counter etc. like we do at home. The ole RV fridge just can't handle that.