My AC unit just will not cool the house down. Everything is running, there is plenty of freon and the compressor seems to be good. All filters are clean and fan is blowing, the only thing I can see is the suction or low side of the compressor pressure is swinging 12 to 15 psi. I don't know what that means, if anything. Can some one please help with a suggestion. Thanks.

Good day. I had a company come out because my air handler was leaking inside the house. Its a vertical 2-ton unit with a slant coil. Apparently there is buildup on the inside of the coil and the buildup at the bottom where the pan drains has clogged. Water drains but not enough and it backs up in the drain pan and comes out of a small weep hole on the side. I tried to vacuum it out from the inside, but I cannot get behind the coil. I dont have experience with this as it is my first home. The company said they would charge over $300 to "pull and clean" the coil and that was needed. I can see on the top part of the inner-side of the coil some bits of black gunk and can only assume its worse below which causes it to backup. I am looking for advice on how to clean that out or even clean the inner-side of the coil without having to remove the coil itself... or maybe an alternative to try? Advice? Many thanks. KDC