I have a 6 year old house on a concrete foundation in Central Texas where there is a lot of rock in the ground. The foundation on one side of my house is always wet and where the foundation meets my back porch slab there is a slow trickle of water. I called my builder's warranty didvision and they sent out a guy. That same side of the house also has my AC drain pipe. When the warranty rep got there he noticed my drain pipe only came out of my wall about 2 inches. He cut a hole in the drywall inside the home and found no moisture. His conclusion was that the water was coming out of the lip of the pipe and traveling along the bottom side of it and back towards my home. I believed him so I cemented a piece of pipe onto the nub so the AC drains about 3 feet away from the wall. Well a month later the moisture is still there. The entire slab is wet from ground level to where the foundation meets the brick and the water is still trickling onto my patio. Any suggestions?
Without seeing the site, it sounds like you may have a spring in your yard. When it rains, the water soaks in above you and seeps along some layer in the subsoil. Your foundation cut into that layer and now dams the flow. If this is the case, you'll need to install a drain uphill of your house to divert the water. Try digging a few small holes to look for wet (as opposed to damp) soil.