How do I work the Kenmore Dual Undersink Water Filter?

I moved into a home with a Kenmore Dual Undersink Water Filter already installed. When I turned it on this little red light was blinking and my sister said that the water tasted funny. We asked the plumber about it, but he didn't have a clue. I took another look at it and found it runs on batteries, so I switched them out. Now when you turn it on, a green light flashes, but the water still tastes funny. Am I supposed to do something else with it?How do I work the Kenmore Dual Undersink Water Filter?Change the filter. Turn off water supply to filter, release water pressure, twist off top, and pull out filter. Sometimes the whole unit needs to be unmounted from cabinet in order to remove filter. Take your old filter and model number with you to walmart, kmart, lowes, or home depot, and they'll fix ya up with a new one