I have a Kenmore 580 air conditioner that seems to freeze up a little or something as it spits out little ice chips and make clanking sounds after running for about 20 mins. When I let the fan run for awhile it seems to melt whatever froze up and the noise and ice chips stop. When I turn the A/C mode back on; however, the ice and noise start again. Any suggestions, cures, etc. out there? Thanks.