Toyota Repair: Camery heating, heater control valve, control cables

Question
I have a 98 Camery with the 2.2liter engine.
The heater does not seem to blow "HOT" air. The fan/blower works fine, but the heat that comes out of the air registers only seems to a few degrees warmer than the surounding air.
What could be wrong?

Answer
Does the temperature gauge on the dash go to normal operating temperature? If not replace the thermostat. If that's not the case then I would suspect that one of the heater control cables has become disconnected or that possibly the heater core is restricted or the heater control valve is not working and is stuck closed.