Daikin DRG0361DL00001S Service Instructions Manual page 41

SYSTEM OPERATION
Automatic Reset High Limit Control (LS)
Located in the burner compartment on the heat exchanger,
its sensing element projects through the blower section
bulkhead and senses the temperature at the rear of the
furnace. It will cycle the furnace off if the temperature
exceeds 100°F plus maximum rise.
Auxiliary High Limit Control (ALS)
Located in the blower compartment on the blower
housing, it senses air temperature within the blower
compartment and protects the filters from excessive
temperature. It will shut down the furnace if it senses
excessive temperatures.
Elevated temperatures at the control are normally caused
by blower failure. The reason for the shut down should be
determined and repaired prior to resetting.
Manual Reset Flame Rollout Control (RS)
Located in the burner compartment at the top of the
burner assembly, it senses high temperature that could
occur if the heat exchanger tubes were plugged and the
flame was rolling out instead of entering the tubes. It has
a manual push-button reset that cannot be actuated until
the limit control has cooled.
The reason for elevated temperatures at the control should
be determined and repaired prior to resetting this manual
reset control.
To avoid property damage, personal injury or death due
to fire or explosion, a qualified servicer must investigate
the reason for the rollout protection device to open
before manually resetting the rollout protection device.
Refrigeration System Checks
This unit is equipped with thermal expansion valves.
Ensure the hold-down bolts on the compressor are secure
and have not vibrated loose during shipment. Check
that the vibration grommets have been installed and
visually check all piping for damage and leaks and repair
if necessary. The entire system has been factory charged
and tested, making it unnecessary to field charge. Factory
refrigerant charge is shown on the unit's nameplate.
WARNING
To confirm charge levels or, if a leak occurs and charge
needs to be added to the system, it is recommended to
evacuate the system and recharge refrigerant to the unit's
nameplate specifications. This unit has been rated in the
cooling mode at the AHRI rated conditions of: indoor (80°F
db/67°F wb) and outdoor (95°F db). While operating at
this condition, the superheat should range from 9°F to
11°F for each refrigeration circuit measured at the suction
service port located near the compressor.
Start-Up Procedure and Checklist
Begin with power turned off at all disconnects.
1. Turn thermostat system switch to "Cool," and fan
switch to "Auto" and turn temperature setting as high
as it will go.
2. Inspect all registers and set them to the normal open
position.
3. Turn on the electrical supply at the disconnect.
4. Turn the fan switch to the "ON" position. The blower
should operate after a 7 second delay.
5. Turn the fan switch to "Auto" position. The blower
should stop after a 60 second delay.
6. Slowly lower the cooling temperature until the unit
starts. The compressor, blower and fan should now
be operating. Allow the unit to run 10 minutes, make
sure cool air is being supplied by the unit.
7. Turn the temperature setting to the highest position,
stopping the unit. The indoor blower will continue to
run for 60 seconds.
Turn the thermostat system switch to "OFF" and
disconnect all power when servicing the unit.
Refrigeration Sequence Check
1. 24VAC control voltage is provided by the control
transformer to terminal XS. The control voltage is
passed through any installed safety shutdown devices
such as the smoke detector before providing 24VAC to
terminals ES and R.
2. To simulate a mechanical call for cooling lower the
room cooling setpoint to a value below the current
room temperature. The cooling is energized when the
room temperature is above the setpoint for cooling.
3. UNIT WITH ECONOMIZER OPTION: The compressor
circuit is interlocked through the economizer module.
If the outdoor air enthalpy (temperature and
humidity) is not suitable for cooling, the economizer
will permit the compressor to be energized.
4. The blower motor is operated to provide cool supply
air to the space.
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