You can buy a radiator"comb" to straighten fins from an auto parts supply or from an RV parts supply. I have had one for about 15 years and used it quite a bit on a window unit and on an RV AC.Beware of bending the cooling fins, whether it's a central unit, window AC, or even a vehicle radiator.
Some will flatten easily with compressed air or water pressure, which greatly reduces air flow. Always try to blow/spray them "straight on" rather than sideways.