We have a fairly new system in our old house. Teh entire system was installed about a year ago. Recently while running the air handler to move some air around my wife noticed a moldy smell. We turned off the sytstem and started investigating. The system has a pump to remove the water from the unit. I checked the line and it was clear. I ran bleach through the pump and it ran through the line and outside. I checked the evaporator and it was covered with what I assume was mold. I got some coil cleaner and cleaned it out with the cleaner and the garden hose. Now about two weeks later we have the same thing. Also,we have kept the filter changed regularly. Can anyone tell me what could be going wrong with the system. Should we not run the air handler without running the a/c?