York D2NA060 User Manual

When the thermostat calls for “HEAT”, the thermostat terminal
“W” is energized, energizing the combustion air blower.

After airflow is established, the air proving switch closes, the
hot surface ignitor is energized and the pilot valve opens ignit-
ing the pilot flame. The system will try to light the pilot for 90
seconds. After 90 seconds, the pilot valve will close and the
system will retry in 5 minutes.

The flame rod senses a flame and de-energizes the ignitor
opening the main gas valve and the main burners light.

30 seconds after the main burners light the circulating fan is en-
ergized at the heating speed.

When the thermostat is satisfied, terminal “W” is de-energized,
de-energizing the ignition system closing the gas valve.

After a 5 second postpurge timing period, the combustion air
blower is de-energized and the heat fan off timing begins.

When this field selected heat fan off timing is completed the cir-
culating fan is de-energized.

If the primary, rollout or auxiliary limit switches open, the ther-
mostat and ignition system is de-energized and the gas valve
closes. The combustion blower and the circulating fan, at heat
speed, are energized.

The combustion blower remains energized for the 5 second
postpurge timing period if the primary, rollout or auxiliary limit
switches remake the contact (the rollout and auxiliary limit

switches must be manually reset). The circulating fan remains
energized for the selected heat delay off timing.

Normal operation of the system resumes.

When the thermostat calls for “COOL”, the thermostat termi-
nals “G” and “Y” are energized signaling the compressor and
outdoor fan to run.

After a cool fan on delay timing of 2 seconds, the circulating fan
is energized at cooling speed.

When the thermostat is satisfied, terminals “G” and “Y” are de-
energized, de-energizing the compressor and outdoor fan.

After a cool fan off delay timing of 30 seconds the circulating
fan is de-energized.

When the thermostat calls for “FAN”, the thermostat terminal
“G” is energized signaling the circulating fan to run at the heat
speed 2 seconds after the “G” terminal is energized.

If a call for “HEAT” occurs, the circulating fan continues to run at
the heat speed.

If a call for “COOL” occurs, the circulating fan switches to cool
speed after a 4 second delay.

When the thermostat ends the call for “FAN”, the thermostat
terminal “G” is de-energized, de-energizing the circulating fan.

035-18265-001-A-0202

Unitary Products Group

9

Complete the following checks before starting the unit.

1. Check the type of gas being supplied. Be sure that it is the

same as listed on the unit nameplate.

2. Make sure that the vent outlet air hoods has been properly

installed.

1. STOP! Read the information on the unit safety label.

2. Set the thermostat to the “OFF” position.

3. Turn off all electrical power to the unit.

4. DO NOT try to light the burners by hand. This appliance is

equipped with an ignition device which automatically lights
the burners.

5. Remove the access panel.

6. Turn the gas valve switch to the “OFF” position.

7. Wait five (5) minutes to clear out any gas. If you then smell

gas, STOP! Follow “B” in the information on the unit safety
label. If you don't smell gas, go to the next step.

8. Turn the gas valve switch to the “ON” position.

9. Replace the control access panel.

10. Turn on all electric power to the unit.

11. Set the thermostat to the desired setting.

12. If the unit will not operate, follow the instructions “To Turn

Off Gas To Appliance” and call your service technician or
gas supplier.

1. Set the thermostat to the “OFF” position.

2. Turn off all electric power to the appliance if service is to be

performed.

3. Remove the control access panel.

4. Turn the gas valve switch to the “OFF” position. DO NOT

5. Replace the control access panel.

After the entire control circuit has been energized and the heat-
ing section is operating, make the following checks:

1. Check for gas leaks in the unit piping as well as the supply

piping.