Can you feel the radiator core iteslf? Your thermostat could be stuck open or the heater core could have restricted flow. Call Jon at Dublin Auto (925)828-0243. He's a factory trained Toyota Tech and can check it for you.
Heater blows hot air only, when the car has warmed up?? Are you looking for cold air as in air conditioning? It can be mechanical or electronic, low on freon or blend doors not opening. call 925-947-2555 Andre or Bart