I have a 2003 Acura TL and the climate control is

Most likely the thermostat itself is going bad. When they fail, they get stuck open so that the engine doesn't overheat. Problem is, the coolant doesn't stay in the engine long enough to absorb enough heat to adequately heat the climate control air. You'll most likely need a new thermostat. They're inexpensive to buy (on my Audi it's a $13 part) but depending on where it is located, it could be cheap or expensive for labor.