No heat air in coolent

Professional help is really needed, because it's difficult to know what might be causing your concern. Jumping to conclusions, one may think there could be an internal engine coolant leak -- causing back-pressure of exhaust gases to build up in the cooling system -- which can cause bubbles. But this isn't the only possibility. Air pockets can happen, especially if recent service to the system has been performed in any way. Seek the professional guidance of a trained technician.