Carrier Debonair 2 Owner's Manual page 18

About Advanced Features & Operation
DEADBAND OPERATION - Controls one Heat and one Cool stage with a three
speed fan (see below).
The low speed fan for heat or cool is turned on when: The temperature
spread from the setpoint is equal to or greater than: the setpoint plus the 1st
stage dead-band (step #6, page 12). This 1st stage deadband is adjustable
from 1-6 degrees and the default is two degrees.
The medium speed fan for heat or cool is turned on when: The temperature
spread from the setpoint is equal to or greater than: the setpoint plus the 1st
stage deadband (step #6, page 12), plus the 2nd stage dead-band. This 2nd
stage deadband is fixed at one degree and is not adjustable.
The high speed fan for heat or cool is turned on when: The temperature
spread from the setpoint is equal to or greater than: the setpoint plus the 1st
stage deadband (step #6, page 12), plus the 2nd stage deadband, plus the 3rd
stage deadband. This 3rd stage deadband is fixed at one degree and is not
adjustable.
1˚
DB3
Hi- Med-
speed speed
fan
DECREASE
The above figure assumes the minimum on time for the prior stage has been
met to allow the next stage to turn on, once the deadbands have been exceeded.
Heating
1˚ 1˚-6˚
DB2 DB1
Lo- Heat
speed SP
fan fan
TEMPERATURE
Cooling
1˚-6˚ 1˚
DB1 DB2
Cool Lo-
SP speed
fan
INCREASE
17
1˚
DB3
Med- Hi-
speed speed
fan fan