How do I identify what’s wrong within the hvac system?

Hello, this concern could be due to a climate control problem where the door that moves from hot to cold does not work as it should. It could be that the engine temperature isn't what it should be. It could be that the air conditioning system does not put out cold air as it should. A little more observation needs to be done to find out what the symptoms are and then diagnostic testing based on those symptoms needs carried out.