1996 camaro fan help

We have a 1996 V6 3800 Camaro with an overheating problem. We can run it for
hours in the driveway and it works great. Fan #3 (rightside) kicks on at
approx 215 degrees and pulls it back down to about 180. fan control 1 & 2
(leftside) never kicks on. While driving it never overheats, but in traffic
just idling it rises up and pegs the gauge very quickly. I try to duplicate
the same thing in the driveway and it never overheats. I try sitting in gear
moving a little at a time up the drive and fan #3 (right side fan) kicks in
and keeps it cool. I've had it overheat in traffic and come straight home
and sit in the driveway in gear just like it was when it overheated and it
works like it should and doesn't overheat.
We bled the cooling system today it had a little air in it (out of the
bleeder on the thermostat outlet)
P.S. We also swapped the relays around and it still only runs the one fan.
What does it take to run the leftside (big) fan ?
Thanks