I have an older model Maple Chase thermostat that is battery operated and programmable. I made the mistake of removing both batteries at the same time to replace them then later read to only remove one at a time. I think I programmed it correctly, but it does not seem to be working correct. Any ideas?

Please explain "not working correctly".

The fan comes on when I set it to on but I don't feel cold air blowing out of the vents

Is the outdoor unit running? If so, in addition to the sound of the fan, can you hear anything else?