Your heater will blow cold air only.
you may not have the heater water hoses plugged in
It doesn't really blow it out it just warms the cold air.
You are low on coolant to the heater core.
replace front heater corefront and rear have independent heater cores
check your coolant level
Thermostat and/or heater core may be defective
Could be the Climate Control Unit or Clogged heater core.
Low coolant in the system. Defective heater control valve. Clogged heater core.
The front expansion valve is clogged.
it wont blow heat itll blow cold air
you are low on coolingliquid !