Kenny, it's a known fluorescent ballast interference (with thermostat operation) issue...
1. Turn the thermostat "off"
2. Turn off ALL fluorescent lights
3. Wait 20 seconds
4. Turn thermostat/air condition(s) back on
"Ghost" zone 3 and possibly zone 4 may still be shown on the thermostat display screen, but this will not interfere with the operation. Just ignore it. To get rid of the ghost display, remove momentarily and re-insert the low voltage thermostat control fuse (under bed in bedroom).
At this point, you can isolate the culprit fluorescent light by turning each one (individually) "on," wait a few minutes, and see what light triggers the interference. In my case, both the bedroom and the kitchen lights were the culprit. I simply leave them off while running the AC. You may choose to replace the existing 12VDC/110VAC ballast assembly with 12VDC only lights.
2002 Fleetwood Revolution 38B