With the engine at full operating temp, locate the 2 heater hoses where they go into the firewall and feel them to see if they are both hot to the touch. If they are both hot, the heat in that vehicle is controlled by a blend door that regulates heated air flow. it is operated by an electric motor/actuator. The problem can be that the actuator is stripped or inoperative or the door itself could be damaged. This is what needs to be determined by examining the actuator and see if it is responding to heat change commands or not.

Unfortunately I have NO IDEA where those are located. I understand where the firewall is...but are they located inside on passenger side? Also, do I have to rip anything apart to get to them to feel them? Other people have been saying to check them, but I don't know where they are at specifically to be able to check. Would that cause a fluctuation with my temperature gauge? I feel so lost... :(

Sound like you need to get this to a professional ASAP. This isn't something to experiment on. It can cost you a motor quick.