Hi. My 2014 frontier is not putting out warm air. I'm definitely good on coolant. The coolant seems to be flowing the system and heater core just fine. I can change where the air goes(defrost vs feet), but the temperature doesn't change regardless of where I have to temperature knob. I'm thinking it's probably the blend door actuator, is there a way to test this at home? Has anyone done this replacement and have any tips to offer? Thank you!