Hello, After having no cooling, I had a service man add some freon and now it's cooling well. However, a new problem has now surfaced. Water is pouring into the furnace because the drip pan for the "a" coil is rusted out. I just opened it up and slid the a coil out for access. I have the pan removed and the outside dimensions are 21.5 x 15.5 It is totally destroyed by the rust. The outside unit is a Rheem and I suppose that is the brand of the "a" coil. Is it common to replace the pan. Is the pan available seperately. Any other advise on how to get the part? Thanks