When I change the coolant on my 2000 S10 Blazer I do the following to get the air out of the system. I drive the truck up on ramps to get the radiator as high as possible. I leave the radiator cap (not the reservoir) off with the engine running and the heater turned on high. As the engine warms up the air should work its way of the system. I top off the radiator as needed, once the coolant starts to overflow the radiator cap, I replace the cap.
Ed B.