Bought house summer 2010. A/C has been working fine since then until past wkend. Compressor turns on/off as thermostat calls, but air handler fan stays on continuously.

Fan stays on after removing thermostat (Hunter) from wall. Replaced thermostat. Took access panel off air handler, found White Rogers 50A65-475 IFC. Probed thermostat inputs (terminal block) on IFC with multimeter (holding panel kill switch closed). Found 25VAC on R (red), <1VAC on all other inputs, including G (green) and Y (Blue not Yellow in this case). Red LED on IFC blinks slowly. Fan running the whole time, except when kill switch opened. When kill switch closes, can hear relay on IFC close before fan comes on.

My conclusion is drive circuit for fan relay is hosed and keeps relay and thus fan ON. I see replacements for IFC all over internet, but prices start ~$135, so I would like to see if there might be another answer.

SO - does this sound familiar, and is there a cheaper fix than replacing the IFC? If the IFC can be repaired relatively easily, I have experience replacing parts on PCBs.