Carrier RG66B3/BGEF Owner's Manual page 12

Setting both TIMER ON and TIMER OFF at the same time
Keep in mind that the time periods you set for both functions refer to hours after the current
time. For example, say that the current time is 1:00 PM, and you want the unit to turn on
automatically at 7:00 PM. You want it to operate for 2 hours, then automatically turn off at
9:00 PM.
Do the following:
1
Timer
5
Timer
2
or
6
or
3
7
11
4
3
sec
8
3
sec