Why is it that the heater only blows cold air

First make sure your coolant is full, then is your engine reaching normal operating temperature ( 180-200deg). Then check to see if the heater hoses are hot to the touch on both hoses. If that is all good then we move inside the car.

Make sure your coolants level is good then check the temp at the inllet and outlet of theheater core hoses.could be low coolant level ;thermostat, clogged heater core or heater plenum concerns