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C C o o n n t t r r o o l l W W i i r r i i n n g g ( ( C C l l a a s s s s I I I I ) )
Low voltage control wiring should not be run in conduit
with power wiring unless Class 1 wire of proper voltage
rating is used. Route the thermostat cable or equivalent
single leads of No. 18 AWG colored wire from the
thermostat subbase terminals through the rubber
grommet on the unit. See Unit Clearance Drawings for
the control entry (24V Entry) location. Make
connections as shown on the wiring diagrams.
Do not short thermostat wires since this will damage
the control transformer.
Refer to the table below for recommended wire sizes
and lengths for installing the unit thermostat. The total
resistance of these low voltage wires must not exceed
one (1) ohm. Any resistance in excess of 1 ohm may
cause the control to malfunction because of the
excessive voltage drop.
Table 7. Thermostat Wire Size and Maximum Length
Wire Size
18
16
14
I I m m p p o o r r t t a a n n t t : : Upon completion of wiring, check all
electrical connections, including factory
wiring within the unit, and make sure all
connections are tight. Replace and secure
all electrical box covers and access panels
before leaving the unit or turning on the
power to the unit.
Step 5 — Unit Startup
P P r r e e - - S S t t a a r r t t Q Q u u i i c c k k C C h h e e c c k k l l i i s s t t
☐ Is the unit properly located and level with the
proper clearances? See
Clearances," p. 5
☐ Is the duct work correctly sized, run, taped,
insulated, and weatherproofed with proper unit
arrangement as shown in the ductwork installation
section?
☐ Is the condensate line properly sized, run, trapped,
and pitched and shown in the Condensate Drain
Piping section?
☐ Is the filter of the correct size and quantity? Is it
clean and in place? See Air Filter Installation
section.
☐ 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 well located, level, and correctly
wired? See Electrical Wiring section
18-EB33D1-1D-EN
Maximum Length (Ft)
75
125
200
"Step 2 — Determine Unit
S S t t e e p p 4 4 — — U U n n i i t t I I n n s s t t a a l l l l a a t t i i o o n n
☐ Have the air conditioning systems been checked at
the service ports for charge and leak tested if
necessary?
☐ Do the condenser fan and indoor blower turn free
without rubbing and are they tight on the shafts?
☐ 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?
S S t t a a r r t t i i n n g g t t h h e e U U n n i i t t i i n n C C o o o o l l i i n n g g M M o o d d e e
N N o o t t e e : : 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 comfort
control to C C O O O O L L and to a setting below room
temperature. The condenser fan motor, compressor
and evaporator fan motor will operate automatically.
Continuous fan mode during Cooling operation may
not be appropriate in humid climates. If the indoor air
exceeds 60% relative humidity or simply feels
uncomfortably humid, it is recommended that the fan
only be used in the A A U U T T O O mode.
O O p p e e r r a a t t i i n n g g P P r r e e s s s s u u r r e e C C h h e e c c k k s s
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
(behind the Compressor access panel). Check the
suction and discharge pressures and compare them to
the normal operating pressures provided in the unit's
SERVICE FACTS.
N N o o t t e e : : 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 SERVICE
FACTS.
V V o o l l t t a a g g e e C C h h e e c c k k
With the compressor operating, check the line voltage
at the unit (contactor is located behind the Control
access panel). 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.
C C o o o o l l i i n n g g S S h h u u t t D D o o w w n n
Set the comfort control to O O F F F F or to a setting above
room temperature.
I I m m p p o o r r t t a a n n t t : : De-energize the main power disconnect
ONLY when servicing the unit. Power may
be required to keep the heat pump
compressor warm and to boil off
refrigerant in the compressor.
19
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