Cfm / Timer Board; Heating Airflow - York P XD-V Series Service Manual

035-19643-001 Rev. B (0204)
6. 1st and 2nd Stage satisfied simultaneously
• Both stages of the Gas Valve are de-energized.
• Flame Rectification is lost.
• The Inducer and Hum relays are de-energized after a 15-second
post purge.
• 30 seconds later the Control shifts the Blower from Heat High to
Heat Low.
• After the Blower-Off Delay Circuit is satisfied, the Blower and
EAC are de-energized.
7. Manual Fan Operation
• With the thermostat in the Fan On position, a circuit is completed
between R and G of the Control.
• The Heat Low and EAC relays are energized by the Control.
8. Call for Cooling
• The thermostat closes two circuits R to Y and R to G. Since the
Outdoor Unit is connected to Y and C at the Control, it is ener-
gized.
• The Cool and EAC relays are energized by the Control.
• A Blower-Off Delay Timing Circuit is energized by the call on Y.
9. Cooling call satisfied
• The thermostat opens the R to Y and R to G circuits.
• The Outdoor Unit is de-energized.
• The 60-second, Blower-Off Delay, timing circuit is initiated.
• After 60 seconds, the Cool and EAC relays are de-energized.

CFM / TIMER BOARD

Variable speed motors will adjust the motor speed in order to maintain
the indoor fan CFM. The CFM / Timer Board is used to control the
blower speed thus the CFM when the unit is operating in the heating or
cooling modes. The blower CFM for cooling can be modified by chang-
ing the jumper pin position on the taps selection marked COOL and
ADJ.
The blower CFM for heating can be modified by changing the jumper
pin position on the taps selection marked HEAT and ADJ. The taps
selection pins have been preset at the factory to provide the maximum
CFM. Table 16 in the installation manual list the recommended jumper
pin settings.
If a lesser CFM is required for a specific HVAC system the taps selec-
tion pins can be moved to the "B", "C", or "D" positions. Pin "A" will pro-
vide the highest CFM and "D" will provide the lowest CFM. The taps
selection marked DELAY are used for cooling only. The recommended
settings for these jumper pins are listed in Delay taps selection.

HEATING AIRFLOW

The heating airflow has been preset at the factory to provide maximum
CFM. If a lesser CFM is required for a specific HVAC system the
"JUMPER" on the HEAT selection pins on the CFM-Timer Board may
be moved to tap "B", "C", or "D".
BLOWER MOTOR
CONNECTIONS
TWO STAGE VARIABLE SPEED THERMOSTAT CONNECTIONS ONLY
FIGURE 7: CFM / Timer Board
6
HEAT Taps Selection on the CFM / Timer Board
Pin Position A: will provide the highest CFM.
Pin Position B and C: are the medium and medium low CFM settings.
Pin Position D: will provide the lowest CFM.
Refer to Table 16 in the installation manual for the proper "HEAT"
Taps Selection for the model furnace you are installing.
NOTE: When changing jumper positions, make sure that the jumper is
pushed all the way on the pins. If the jumper is not making good
contact or is left off completely, the blower will operate as if the
jumper were in the "A" position.
NOTE: Power to the blower must be removed for at least 4 seconds
after a heat or cool tap selection change, in order for the motor
to recognize an adjustment. The fixed blower on delay and
adjustable blower-off delay will function as described in the
"OPERATION AND MAINTENANCE" Section in the Users Infor-
mation Manual.
Heating Indoor Fan Off Delay
Changing the dipswitches on the Integrated Control can change the
indoor fan "OFF" time delay. The dipswitches are located above the
thermostat terminals. Refer to Figure 8 for the dipswitch settings to
obtain the desired fan OFF delay. The blower off delay must be long
enough to adequately cool the furnace, but not so long that cold air is
blown into the living space.
The blower on delay is fixed at 30 seconds and cannot be adjusted.
The continuous fan speed dipswitch (switch # 3 on the Integrated Con-
trol) does not function on variable speed models. Dipswitch # 3 should
be left in the off position.
FIGURE 8: White Rodgers Intergrated Control
Continuous Blower:
There are two modes of continuous blower operation.
• Mode One: The blower is controlled directly through the blower
motor. In the first mode, when the thermostat fan-switch is set to
the ON position a circuit is completed between terminals "R" and
"G" of the thermostat. The continuous fan speed will be 63% of
the high cool speed. If more air is desirable the green wire
labeled (G Cool Speed) may be connected to the "G" terminal of
the ignition control to achieve HIGH COOL speed (DIP switch
number 3 on the ignition control must be in the OFF position).
• Mode Two: The blower is controlled through the ignition control.
This configuration is used with multi-speed direct drive PSC
motors. Do not use this configuration with a variable speed
motor. Refer to Heating Indoor Fan Off Delay for Fan ON / OFF
Delays.
The air cleaner and the blower motor are energized through the ignition
control or directly through the motor.
INDOOR FAN OFF
DELAY DIP SWITCHES
Unitary Products Group