4
!
WARNING
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or
death.
Before performing service or maintenance, be sure indoor unit
main power switch is turned OFF and indoor blower has
stopped.
Power Wiring
Unit is factory wired for voltage shown on nameplate. Provide
adequate, fused disconnect switch within sight from unit, readily
accessible, but out of reach of children. Provision for locking the
switch open (off) is advisable to prevent power from being turned
on while unit is being serviced.
Disconnect switch, fuses, and field wiring must comply with the
NEC and local code requirements. Use copper wire only between
the disconnect switch and unit. Use minimum 75 C wire for the
field power connection.
Route power wires through the opening in unit side panel and
connect in the unit control box as shown on the unit label diagram
and Fig. 4. Unit must be grounded.
LEGEND
NEC
—
National Electrical Code
TB
—
Terminal Board
TB Connections
Field Wiring
Factory Wiring
—
—
A07428
Fig. 4
-
Line Power Connections
Control Circuit Wiring
Control voltage is 24 v (40 va minimum). See Fig. 5 and unit label
diagram for field
−
supplied wiring details. Route control wire
through opening in unit side panel to connection in unit control
box.
A07398
Fig. 5
-
24AHA4 Typical Control Circuit Connections
NOTE
: Use No. 18 AWG color
−
coded, insulated (35
_
C
minimum) wire. If thermostat is located more than 100 ft. (30.5 m)
from unit, as measured along the control voltage wires, use No. 16
AWG color
−
coded wire to avoid excessive voltage drop.
NOTE
: All wiring must conform to NEC and local codes.
NOTE
: Operating unit on improper line voltage constitutes abuse
and could affect warranty. See Product Data.
Do not
install unit in
a system where voltage may fluctuate above or below permissible
limits.
Refer to the Product Data for recommended fuse sizes. When
making electrical connections, provide clearance at the unit for
refrigerant piping connections.
NOTE
: The 24AHA4 units use the control transformer supplied
with the matched indoor unit.
START
−
UP
PRELIMINARY CHECKS
1. Check that all internal wiring connections are tight and that
all barriers, covers, and panels are in place.
2. Field electrical power source must agree with unit name-
plate rating.
3. All service valves must be open.
4. Belly
−
band crankcase heater must be tight on compressor
crankcase for those units with belly
−
band heaters.
EVACUATE AND DEHYDRATE
Field piping and fan coil must be evacuated and dehydrated.
CHARGE SYSTEM
Release charge into system by opening (back
−
seating) liquid and
suction line service valves. Outdoor unit is charged for 15 ft (4.6
m) of 3/8
−
in. liquid line.
TO START UNIT
Be sure that the field disconnect is closed. Set room thermostat
below ambient temperature. Operate unit for 15 minutes, then
check system refrigerant charge. See Refrigerant Charging section.
SERVICE
!
WARNING
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
Before installing, modifying, or servicing system, main
electrical disconnect switch must be in the OFF position.
There may be more than 1 disconnect switch. Lock out and
tag switch with a suitable warning label.
High
−
Pressure Relief Valve
The high
−
pressure relief valve is located in the compressor. The
relief valve opens at a pressure differential of approximately 550 to
625
±
50 psig between suction (low side) and discharge (high side)
to allow pressure equalization.
Internal Current and Temperature Sensitive Overload
The control resets automatically when internal compressor motor
temperature drops to a safe level (overloads may require up to 45
minutes to reset). When an internal overload is suspected of being
open, check by using an ohmmeter or continuity tester.
Pumpdown Procedure
The system may be pumped down in order to make repairs on the
low side without losing complete refrigerant charge.
CAUTION
!
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage or improper operation.
Never open system to atmosphere while it is under a vacuum.
When system must be opened for service, recover refrigerant, break
vacuum with dry nitrogen before opening system.
1. Attach pressure gage to suction service valve gage port.
2. Front
−
seat the liquid/mixed phase line valve.
