frigidaire fridge. coils frosting up

[69machrk]

i have a frigidaire fridge. model #FRS26W2AW4 that keeps frosting up the coils in a weeks time.we were without power a few weeks ago for a week so i used a generator to power a few things in the house for about a week. now that power has been restored my fridge keeps frosting up. once defrosted it works great for about a week then frosts up. i know it has to be the defrost timer, the circuit board, heater, or timer but can someone narrow it down for me. i do have a meter to check the different circuits.

[RegUS_PatOff]

FRS26W2AW4 Parts Manual (ftp://ftp.electrolux-na.com/ProdInfo_PDF/Anderson/5995367595.pdf)

FRS26W2AW4 Wiring Diagram (ftp://ftp.electrolux-na.com/ProdInfo_PDF/Anderson/240389607.pdf)

[69machrk]

thanks..... that will help out alot, great site for all of us d.i.y's