Question: how do you know if your radiator has air in it?
Answer: Overheating engine. A common sign that something is wrong with the radiator is when your engine starts to overheat. ... 
Leaks. ... 
Shifting issues. ... 
Fluid discoloration. ... 
Exterior fins blocked. ... 
Passenger heater not functioning. ... 
Checking the Cooling System. ... 
Heater core.