For a dual zone AC system, do you need the exact thermostat model for both upstairs and downstairs (and do the schedules need to match)? I replaced a programmable thermostat upstairs (analog display conked out partially) with a newer model and now the downstairs AC isn't working. (I also just had an AC repair man come out to fix the system because after I had replaced the thermostat, the AC STILL wasn't turning on). It's pretty obvious I have no idea what I'm doing and before I call the repair service again, I want to make sure I didn't mess something up.