2005 Grand Prix GTP.
The other day I was checking the fluid levels, and I noticed that the coolant reservoir was almost completely empty when the engine was cold. So I added some DEX 50/50 coolant to the reservoir (about 3/4 full).
Now the heater blows out cold air, even after driving for 20 minutes. Is it possible that when I added the coolant to the reservoir, that it got air in the coolant lines because it was nearly empty before?
Thanks,
Jeff