heater blows out cold air

Sounds like your thermostat has failed and thankfully stuck open. When this happens your car will not get up to running temperature. If it was the other way, stuck closed your could overheat. One way to know for sure: - when the car is cold. - Lift Hood and feel the top hose going from the engine to radiator. - Then turn on car and feel again If you feel coolant/water moving through when you first turn it on and it is cool/cold then your thermostat is stuck open or missing, sometimes people will remove if it gets stuck closed. Simple DIY repair, but make sure to keep track/a hold of those bolts when you remove the thermostat housing. I lost one and had to get a ride to get a replacement one, not fun.