Sounds like a blend door problem to me... The blend door controls the mixture of cold/warm air coming into the car. When the blend door actuator decides to crap out it gets stuck in the same position and will not move. Thus, no matter what you adjust the temperature to, it will stay the same temperature as when it got stuck (crapped out, lol). I am not familiar with how the dash comes apart in a '95 T/C, but 99% chance what you need is the "blend door actuator"
Good Luck!