my air will turn on in the house(air handler). but the condenser(outside unit) only hums. it will not click the fan on. There is definate power going to the condenser because I can hear it humming. Ive checked the thermostat. And Ive looked for an on/off switch on the condenser or a reset button, but didnt see one. It worked just fine last fall. Please tell me what could be wrong. Thanks, T. Thornton