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room temperature. The outdoor fan motor, compressor, and
evaporator fan motor will operate automatically.
Operating Pressures
After the unit has operated in the cooling mode for a short 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.
Voltage
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
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 selector switch in the OFF position or reset
the thermostat at a setting above the room temperature.
•Do not de-energize the main power disconnect except when
the unit is to be serviced. Power is required to keep the
compressor crankcase heat (if equipped) energized and boil
off refrigerant in the compressor.
SYSTEM FAULTS
REFRIGERANT CIRCUIT
REFRIGERANT CIRCUIT
Liquid Pressure Too high
Liquid Pressure Too Low
Suction Pressure Too High
Suction Pressure Too Low
Liquid Refrigerant floodback (TXV System)
Liquid Refrig. floodback (Cap. Tube System)
I. D. Coil Frosting
Compressor Runs Inadequate or No Cooling
ELECTRICAL
Compressor & O.D. fan Do Not Start
Compressor Will Not Start But O.D. Fan Runs
O.D. Fan Won't Start
Compressor Hums But Will Not Start
Compressor Cycles on IOL
I.D. Blower Won't Start
P-PRIMARY CAUSES S-SECONDARY CAUSES
Start-Up
TROUBLESHOOTING CHART
Start-Up
Starting the Unit in the Heating Mode
NOTE: See the section on "Sequence of Operation" for a descrip-
tion of the heating operating sequence.
•Check to make sure that all grilles and registers are
open and all unit access doors are closed before start-up.
•To start the unit in the heating mode, set the thermo-stat
system switch to HEAT. Move the thermostat
HEAT indicator to a setting above room temperature
and place the fan switch in the AUTO or ON positions.
The indoor fan motor will operate automatically.
•The thermostat must provide a "G" signal for fan operation.
If using an auto changeover thermostat, see Figures 5 and 6
for the appropriate connections.
Heating Shut-Down
•Place the system selector switch to the OFF position or place
the heating selector lever at a setting below the room
temperature.
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