How do I get rid of fruit flies in my fridge?
The fruit flies have laid eggs somewhere in your fridge.  If there are any drain traps or any extra covers for electric/whatever take them off.  Spray the entire fridge with a spray cleaner that has bleach.  Then unplug fridge and let it dry out.  

If during the exercise you find holes that are good possibilities of breeding grounds, plug them with tape.    We find fridges that are very usable in this state very often during flips and the first things we do is bleach the inside (409 makes a spray and a gel that works good - the gel on the bottom).  After it sits for a day we clean with soap and water and let it dry.  Then plug it in and almost all of the time - given seals are good never - no insect issues.