Press the up or down arrowhead key until the word HEAT is
flashing on the PC8900A display.
The PC8900A/W8900A-C is designed to be used on most
types of heating systems. Initially, the PC8900A/W8900A-C
are factory-set to be used on the following systems:
PC8900A/W8900A,C models: Stage 1 and 2 heat:
Conventional noncondensing gas or oil fired furnace
(six cycles per hour at 50 percent load).
PC8900A/W8900B models: Stage 1, 2 and 3 heat: Heat
pump (three cycles per hour at 50 percent load).
The cycle requirements for each stage of heat can be
changed to match the type of heating system used. See Table
5 for the cycle rate options available and the equipment that
corresponds with each cycle rate.
When COOL is flashing, see Table 6 for options for the cooling
equipment stages that appear in the display in the following
order after each press of the CHECK key.
Option not used on the W8900B model.
The Comfort Center™ control panel must have 24 Vac to
The current day and time need to be set. This activates the
preprogram in the Comfort Center™ panel. See Table 8 for the
Table 8. PC8900A Preprogram.
LEAVE (8:00 AM)
RETURN (6:00 PM)
SLEEP (10:00 PM) (62°F)
Table 7. Fan Setting Options.
When PC8900A calls for heat,
PC8900A also calls for fan
No fan overrun in cooling.
Table 6. Cooling Cycle Rates.
Natural gas air
Use these cycle rate settings if faster or slower cycling is
When FAN is flashing, refer to Table 7 for the options
pertaining to the fan equipment that appear in the display in
the following order after each press of the CHECK key.
Other Choices (Press
Up or Down Arrowhead
Keys to Change)
Setting the Current Day and Time
Always press the keys with a fingertip or similar
blunt tool. Sharp instruments like a pen or pencil
point can damage the keyboard.
Check the Glossary section for definitions of
1. Press SET CLOCK. The display shows a time and day.
2. Press and hold DAY until the current day appears in the
3. Press and hold a TIME key until the current time
appears in the display. Be sure AM or PM appear as
4. Press RUN to exit the SET CLOCK program mode.
Y1 CPH 3
Y1 CPH 9
Y1 CPH 6
Y1 CPH 1
Y1 CPH NC
Y1 CPH 4.5
Y1 CPH 2.5
Y1 CPH 2
Y1 CPH 1.5
When PC8900A calls for heat, fan is
energized by equipment
80-second fan overrun after PC8900A
ends call for cooling.
Y2 CPH 3
Y2 CPH 9
Y2 CPH 6
Y2 CPH 1
Y2 CPH NC
Y2 CPH 4.5
Y2 CPH 2.5
Y2 CPH 2
Y2 CPH 1.5