Inside ac is about 2 years old. Inside blower will not shut off. I have since then replaced thermostat with no change. Started turning on and off on it's own even when AC was off then now it always stays on even though I have AC off and blower on auto. It would even stay on when I completely disconnected thermostat. I have to turn off main breaker so it can stop. Cools great just have this issue. Just want to buy the correct part. I have a carrier model number fx4dnf049 . Would you know if it's a relay or control board or am I totally wrong?