Daikin M Series Service And Troubleshooting page 9

SYSTEM OPERATION
1. Low and high stage compressor outputs are
energized.
2. Condenser fan motor is energized at high speed.
3. Air circulating blower is energized at high cool speed
after cool ON delay expires. Cool ON delay timer
begins when thermostat inputs are detected.
Control monitors thermostat, gas valve, flame, and IDT/
ODT/Pressure/Loss of Charge Switches during high stage
cooling operation.
Thermostat "Y1" and "Y2" or "Y1", "Y2" and "G" inputs are
removed.
Low and high stage compressor outputs are de-energized.
High speed condenser fan motor is de-energized.
4. Air circulating blower switches to low cool speed for
the cool OFF delay. Cool OFF delay timer begins
when thermostat input is removed.
Control returns to Standby and awaits next thermostat
request.
A. Continuous Fan Operation
1. Thermostat "G" input initiates Continuous Fan
operation.
2. Air circulation blower shall be immediately energized
at the continuous fan speed. For purposes of this
specification, the continuous fan speed shall be the
low heat speed.
3. Thermostat "G" input is removed.
4. Air circulation blower is immediately de-energized.
5. Control returns to Standby and awaits next
thermostat request.
Heat Pump Operation
Heat Pump Mode Operation Sequence of Operation
1. The thermostat sends a 24VAC signal on Y to the
unit requesting heating.
2. Contactor energizes starting compressor and outdoor
fan
3. Request sent to indoor blower motor for heating
speed. Blower starts after 6 second blower on delay
4. The unit is now operating the heat pump in the
heating mode
5. Once the thermostat satisfies, the Y terminal opens
ending the call for heating.
6. Compressor & Outdoor Fan deenergize
7. Indoor blower motor shuts off after the 60 second
programmed fan off delay.
Heat Pump to Gas Heat Sequence of Operation
NOTE: If the heat pump cannot satisfy the load, the
sequence of operation changes and the unit will switch
from the heat pump to gas heating.
1. The thermostat sends a 24VAC signal on Y to the
unit requesting heating.
2. Contactor is energized starting the compressor and
outdoor fan.
3. Request sent to indoor blower motor for heating
speed. Blower starts after 6 second blower on delay.
4. The unit is now operating the heat pump in the
heating mode.
5. If the thermostat cannot be satisfied, or the outdoor
thermostat changes to gas heating operations, W1 is
energized, and Y is de-energized.
6. The compressor and outdoor fan are turned off.
7. Gas heating cycle begins.
Heating Cycle (Natural Gas/LP)
1. The Dual Fuel unit will operate in gas heat mode
when the thermostat calls for a W-1 or W-2 signal. If
outdoor thermostat is installed, the unit will operate in
gas heat when ambient is below set point or the unit
receives call for low or high stage gas heat.
2. Induced draft blower energizes for 15-second pre-
purge.
3. A 7-second trial for ignition begins by energizing the
low and high stages of the gas valve along with the
spark igniter.
NOTE: The igniter produces a very intense electrical
spark that ignites the gas.
4. Main burners light and control detects presence of
flame.
5. If the call is for low stage heat, the induced draft
blower switches from high to low speed and the gas
valve from high to low stage within 5 seconds after
the main burners light. If call is for high stage heat,
induced draft blower remains at high speed and high
stage gas valve remains open.
NOTE: If a W2 is not used, the control will step to
low stage after the main burners light and remain at
low stage for 5 or 10 minutes, depending on jumper
position. If the jumper is set to none, you will never get
a call for high stage heat. If the call for HEAT remains
after the transition delay time expires, the control will
transition from low stage to high stage.
6. The 30-second HEAT FAN ON delay time begins
after the main burners light.
7. The unit delivers heat to the conditioned space until
the thermostat is satisfied.
8. Gas valve(s) de-energizes. The induced draft blower
continues operation for a 30-second post-purge.
NOTE: Induced draft blower remains at low speed (or
switches from high to low if operating at high stage
heat) for the 30-second post purge.
9. Ignition control begins timing the HEAT FAN OFF
delay. There is an adjustable HEAT FAN OFF delay
of approximately 90/120/150/180 seconds (factory
set at 150). If the unit is operating at high stage when
the call for heat is removed, the blower will operate
for 30 seconds at high heat speed then switch to low
heat speed for the remainder of the selected HEAT
FAN OFF delay.
9