I have a Carrier AC / Model 38CKC018340. We replaced the capacitor a couple of years ago, and last year had an issue with ants getting into the contactor (think that's what the relay switch is called?). I got in there with an emery board on the contacts and got it working again. This year, it's been running fine up until this weekend. Same symptoms as before - a single click when the thermostat is engaged. The capacitor doesn't appear to be swollen. I (gently) banged on the contactor and cleaned the contacts again. Started working. Now, a day later, it's doing the same thing. There appeared to be a couple of ant bodies that came out when I banged on it this weekend, but didn't see anything today. And after banging and cleaning it still wouldn't work. Is this just a bad contactor now? Are they easy enough to replace? Should I take it off of the unit and try and do a thorough cleaning on the contacts? Might there be something else causing this? Like I said, just the single click. Not the buzzing/clicking of a stuck motor. Any help would be appreciated.