I'm about to purchase a condo with the original heat pump from 1983, GE Weathertron. I wish I had pics but the condensing unit is complete rust, a real eyesoar. I don't think the prior occupant used a filter cause the evaparator coil is completely gunked. I have no idea how, but the thing still works fine (measured a LAT of around 98 on a 45 degree day). Did I mention that it's about 100 yards from the ocean? I will be purchasing an appliance warranty first thing no doubt. What is the most likely method of failure I can expect from this thing?