Ahh ...no filter. Ok, if indeed your incoming water pressure is adequate (20-100 psi), this water valve has a hose bib type connection and a screen filter in the throat...may need to dig it out and get the sand and crap out of it...if this is clear, you need a new water valve.

Part link to the new water inlet valve, if needed.

Source: Frigidaire gallery refrigerator FRS22XGCB not making ice, slow water flow