13
Two-Stage Models:
The fan runs at low cool speed for the off delay period. This
allows additional cooling from the indoor coil to be trans-
ferred to the conditioned space. Then, the indoor fan stops.
NOTE
: A 180-second anti-short cycle is integral to the con-
trol and prevents recycling of the compressor.
Fan Only
1. Thermostat calls for FAN ONLY by energizing “G”.
2. Approximately seven seconds later, the indoor fan
starts.
Two-Stage Models:
Indoor fan is energized at low heat speed.
3. The indoor fan continues to run for approximately 60
seconds after “G” is de-energized.
Two-Stage Models:
The indoor fan is immediately de-energized once the ther-
mostat “G” is de-energized.
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 installations, or if a major component has been re-
placed, the operation of the unit must be checked.
Check unit operation as outlined in the following instructions.
If any sparking, odors, or unusual sounds are encountered,
shut off electrical power and recheck 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 properly drawn
into the heat exchanger. The rollout protection device is lo-
cated on the burner bracket. The reason for elevated tem-
peratures at the control should be determined and repaired
prior to resetting this manual reset control.
WARNING
T
O 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
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 tempera-
tures 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 cy-
cle, it may cause the secondary limit to trip. Once the blower
compartment temperature drops below the limit reset tem-
perature, the limit will automatically reset.
Secondary
Control Limit
Back of Unit
Secondary Limit Control
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.
Do not force.
7.
Wait five minutes to clear out any gas.
8. Smell for gas, including near the ground. This is im-
portant because some types of gas are heavier than
air. If you have waited five minutes and you do smell
gas, immediately follow the warnings on page 3 of this
manual. If having waited for five minutes and no gas
smell is noted, move the gas control valve switch to the
ON position.
9. Replace the heat exchanger door on the side of the
unit.