I got in this morning and on the way to work noticed that my heater was blowing cold air. Engine temperature did not get above normal operating temperature and I did not smell coolant inside the car. Any suggestions?

How do you remove the radio?

 

Ok I checked my coolant level and it was low. I haven't seen any leakage since I have bought the car and I have had hot air up until this morning. Any suggestions? I have since filled the coolant up to normal levels.