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NOTE: After the HEAT FAN OFF delay time has
elapsed, the blower will de-energize. This allows
any additional heat in the heat exchanger to be
transferred to the conditioned space.
Cooling
1. Thermostat calls for low or high stage cooling.
2. If the thermostat call is for low stage cooling, the com-
pressor and outdoor fan are energized at low stage. If
the thermostat call is for high stage cooling, the com-
pressor and outdoor fan are energized at high stage.
3. The indoor blower will energize approximately 6 sec-
onds later.
4. The unit delivers cooling to the conditioned space until
the thermostat is satisfied.
5. The compressor and outdoor fan will be de-energized
when the thermostat opens.
6. The indoor blower continues to run at low cool speed
for approximately 60 seconds after the thermostat
is satisfied. This allows additional cooling from the
indoor coil to be transferred to the conditioned space.
Then, the indoor blower is de-energized.
NOTE: A 180-second anti-short cycle is integral to the
control and prevents recycling of the compressor.
Fan Only
1. Thermostat calls for FAN ONLY by energizing "G".
2. The indoor blower is immediately energized at the low
heat speed.
3. The indoor blower is immediately de-energized once
thermostat call for FAN is removed.
STARTUP, ADJUSTMENTS, AND CHECKS
Heating Startup
This unit is equipped with an electronic ignition device to
automatically light the main burners. It also has a power
vent blower to exhaust combustion products. On new in-
stallations, or if a major component has been replaced, the
operation of the unit must be checked.
Check unit operation as outlined in the following instruc-
tions. If any sparking, odors, or unusual sounds are en-
countered, shut off electrical power and check for wiring
errors, or obstructions in or near the blower motors. Duct
covers must be removed before operating unit.
Rollout Protection Control
The rollout protection device opens, cutting power to the
gas valve, if the flames from the burners are not proper-
ly drawn into the heat exchanger. The rollout protection
device is located on the burner bracket. The reason for
elevated temperatures at the control must 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.
Rollout Protection on Burner Bracket
Secondary Limit Control
The secondary limit control is located on the top of the
blower scroll assembly. This control opens when elevated
temperatures are sensed. Elevated temperatures at the
control are normally caused by blower failure. The reason
for the opening should be determined and repaired prior to
resetting.
If the power to the unit is interrupted during the heating
cycle, it may cause the secondary limit to trip. Once the
blower compartment temperature drops below the limit reset
temperature, the limit will automatically reset.
Back of Unit
Pre-Operation Checks
1. Close the manual gas valve external to the unit.
2. Turn off the electrical power supply to the unit.
3. Set the room thermostat to its lowest possible setting.
4. Remove the heat exchanger door on the side of the
unit by removing screws.
5. This unit is equipped with an ignition device which au-
tomatically lights the main burner. DO NOT try to light
burner by any other method.
6. Move the gas control valve switch to the OFF position.
14
WARNING
Rollout Protection
Secondary
Control Limit
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