Another Central Air Conditioner QuestionI?

I have central air with 3 zones (heat with oil fired hot air) Zone one first floor. Zone 2 2nd floor and zone 3 (bonus room over a three car attached garage) also on second floor.
Problem: I set zone one to 82 zone 2 to 75 and zone 3 to 75. but zone one is 72 degrees.
I thought it may have been the main thermostat so I replaced it with a new Honeywell but it is still reading the same. 72 cool degrees on the first floor when none of the thermostats are calling for less than 75 and the main one calling for 82. How do I end up with 72 degrees?
Weird!