Page 23
Installer’s Guide
Pre-Start Quick Checklist
Is the unit properly located and level with the proper
clearance? See Figures 1-6, pages 4-9.
Is the duct work correctly sized, run, taped, insulated, and
weatherproofed with proper unit arrangement? See Ductwork
Installation section on page 16.
Is the gas piping correctly sized, run, trapped, and purged of
air? See Gas Piping section on page 16.
Is the condensate line properly sized, run, trapped, and
pitched? See Condensate drain section on page 16.
Is the filter of the correct size and number? Is it clean and in
place? See Air Filter section on page 19.
Is the wiring properly sized and run according to the unit wiring
diagram?
Are all the wiring connections, including those in the unit,
tight?
Has the unit been properly grounded and fused with the
recommended fuse size?
Is the thermostat correctly wired and well located?
Is the W1 to W2 jumper installed at the unit when using a
*CONT802 or *CONT803 Comfort Control?
Have the air conditioning systems been checked at the service
ports for charge and leak tested if necessary?
Does the condenser fan and indoor blower turn free without
rubbing, and are they tight on the shafts?
Has the indoor blower speed been determined and the proper
speed been set?
Has all work been done in accordance with applicable local
and national codes?
Are all covers and access panels in place to prevent air loss
and safety hazards?
Starting the Unit in the Cooling Mode
NOTE: See the section on “Sequence of Operation” for a
description of the cooling operating sequence.
To start the unit in the cooling mode, set the thermostat system
mode to COOL and adjust the cooling setpoint below the room
temperature. Wait for the minimum compressor off time to
elapse. The condenser (outdoor) fan motor, compressor, and
evaporator (indoor) fan motor will operate automatically.
Operating Pressures
After the unit has operated in the cooling mode for a short
period of time, install pressure gauges on the gauge ports of
the discharge and suction line valves. Check the suction and
discharge pressures and compare them to the normal operating
pressures provided in the unit’s SERVICE FACTS.
NOTE: Do not use the PRESSURE CURVES from the unit’s
SERVICE FACTS to determine the unit refrigerant charge.
The correct charge is shown on the unit nameplate. To charge
the system accurately, weigh in the charge according to the
unit nameplate and check subcooling against the Subcooling
Charging Table in the SERIVCE FACTS.
Voltage Check
With the compressor operating, check the line voltage at the
unit. The voltage should be within the range shown on the unit
nameplate. If low voltage is encountered, check the size and
Step 5—Unit Startup
length of the supply line from the main disconnect to the unit.
The line may be undersized for the length of the run.
Cooling Shut Down
Place the system mode to OFF or adjust the cooling setpoint
above the room temperature.
Starting the Unit in the Heat Pump Heating Mode
NOTE: See the section on “Sequence of Operation” for a
description of the heat pump heating operating sequence.
Check to make sure all grilles and registers are open and all unit
access doors are closed before start-up.
The thermostat may be temporarily operated in Manual Test
Mode for the *CONT402 or in Installer System Test mode for the
*CONT802 AND *CONT803. These are modes designed to be
used to “bump” the system on the various capacity stages. Since
the test mode timeouts are 1 minute and 5 minutes respectively
(in the absence of installer key presses), these modes are not
designed to be used as the only means of system checkout.
Normal thermostat operation should be used for operating the
unit for extended periods of time.
To start the unit in the heat pump heating mode, set the
thermostat system mode to HEAT and adjust the heating setpoint
slightly above the room temperature. Wait for the minimum
compressor off time to elapse. The condenser (outdoor) fan
motor, compressor, and evaporator (indoor) fan motor will
operate automatically.
Heat Pump Heating Shut Down
Place the system mode to OFF or adjust the heating setpoint
below the room temperature.
Gas Furnace Heating Cycle
In addition to the heat pump controls, these units are equipped
with a solid-state ignition control that lights the burners each
time the thermostat calls for heat. The burners are extinguished
during the OFF cycle.
NOTE: See the section on “Sequence of Operation” for a
description of the heating operating sequence.
The gas heating section of the unit can be started using the
following procedure:
1. Be sure the thermostat is configured to power up in the Off
mode, or be prepared to change the system mode to Off just
as soon as power is applied to the thermostat in the steps
below.
a. Turn the main shutoff valve on the gas supply line ON.
b. Turn or switch the manual valve on the combination gas
valve ON position.
2. Be sure the burner compartment access panel is in place.
a. Turn on the electrical power to the unit.
b. Change the thermostat mode to Emergency Heat and
adjust the heating setpoint slightly above the room
temperature.
2. When the thermostat calls for heat, the system operates as
follows:
a. The combustion blower is energized.
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