Frigidaire dishwashers do not have removable filters. The designers have optimistically provided self-cleaning filters only. And yet we have all come across a dishwasher that won't drain properly. Unclogging a dishwasher actually has more to do with checking some factors external to the dishwasher than with the dishwasher itself.
Clean out the air gap. If a drain air gap was installed for your dishwasher, check to make sure it's clean. The air gap allows the dishwasher to drain properly. You'll find it mounted on the countertop—usually next to the faucet on the sink. Remove the cover and take a look at it. Use a toothpick to clean it.
Run the kitchen food waste disposal, if you have one. Make sure it's empty. Your Frigidaire dishwasher may be hooked up to it, and it could be causing the clogging. Turn off the power to the waste disposal, then take a look under the sink to make sure that the drain hose isn't kinked. Examine the waste disposal to make sure the knockout plug is removed.
Clean the overfill protector within the dishwasher. Use vinegar-based cleaner. You'll find the overfill protector in the front left corner of the tub; it keeps the dishwasher from overfilling. The overfill protector device itself should move up and down about an inch. If the overfill protector fails, the dishwasher can overfill making the dishwasher appear to be clogged by not draining enough.
Make sure the cycle is complete if the dishwasher appears not to be draining properly. If you open the door of the dishwasher and the drain or dry cycle hasn't finished its run, you could mistake it for a clog. Run the cycle again empty. Running it empty will give the dishwasher a chance to flush itself so that food won't fill the filters.