A coils are not usually easy to get to. They can be accessed by removing them but you should be careful as moving the coil could cause a refrigerant leak. Especially if the coil has been in place for a while. Fittings may come loose or it may be soldered in place and the coil may not come out at all with out disassembling the refrigerant piping. Another way is to leave the coil in place and cut a hole in the duct work above the coil. But again this could be a delicate procedure depending on your set up. The coil is just on the other side of the duct and if you were to cut the wrong area you may cut the coil. This is not that easy to do in many cases due to the lay out of the duct work. By using good quality air filters cleaning the A coil should not be required. But if you think that it needs cleaning, you may want to contact a professional as moving the coil is tricky as well as cutting into the duct work.