I have a 92 Grand Prix sedan 3.1. I have a low coolant light on even though the level is fine., and my heat is, well, cold. To me that means either my blend door isin't working properly, or there is air in the system. The vehicle seems to run pretty cool, which could also mean thermostat, correct? I already bled all the air out of the system, but the heat is still cool.

Thanks in advance for any help.