Why is my fan continuously running when A/C is selected?
It looks like the fan is programmed to be on when in cooling mode. See the programming guide for the TB8220 section “fan schedule” it’s on page 18 of the manual I found. With fan in on it runs all the time, auto only when needed then there are other settings , occ1, unocc1, occ2 and unocc2 , other than this there is a manual override of the fan schedule, so if it runs fine in heat mode but you don’t like the choice in cooling mode you will need to reprogram the thermostat, note if I install a electrostatic filter in a home the default setting to keep the pollen and dust free in the summer is on all the time so I would check for an electrostatic filter just prior to the air handler, if you have one they need to be washed down every month or so based on how much your unit is picking up, once the grid wires are full they don’t catch the dust and pollen, I put the grid in the shower and a hot water rinse is all that is normally needed, if there are smokers in the home a spray with simple green will cut the tar but it may take 2 cycles to get nice clean wires. Let air dry then reinstall, note even with an electrostatic filter there should be at minimum a fiberglass filter prior to the electrostatic to pick up the big particles.