Carrier 59MN7A Instruction Manual download pdf (Page 33)

J--Box Installation

FIRE OR ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal

injury, death, or property damage.

If field--supplied manual disconnect switch is to be mounted

on furnace casing side, select a location where a drill or

fastener cannot damage electrical or gas components.

WARNING

The J-Box is used when field line voltage electrical connections are

made to the furnace wiring harness inside the furnace casing. The

J-Box is not required if a field-supplied electrical box is attached to

the outside of the furnace casing and the box is grounded to the

green ground wire of the main wiring harness and the earth ground

of the field electrical supply.

The J--Box cover, mounting bracket and screws are shipped in the

loose parts bag included with the furnace. The J--Box can be

mounted on the left or right side of the casing, as viewed from the

upflow position.

Remove the J--Box cover and mounting bracket from the loose

parts bag. Select a 7/8--in. (22 mm) knock-out on the desired side

of the casing. Remove the knock-out from the casing. Drill two (2)

1/8--in. (3 mm) pilot holes in the casing dimples by the desired

7/8--in. (22 mm) knock-out.

Align the J--box mounting bracket against the inside of the casing

and secure the mounting bracket with the screws. (See Fig. 30.)

Electrical Box on Furnace Casing Side

NOTE: Check that duct on side of furnace will not interfere with

installed electrical box.

1. Fasten a field-supplied external electrical box to the outside

of the casing by driving two field-supplied screws from in-

side electrical box into casing. (See Fig. 31.)

2. Route field power wiring into external electrical box.

3. Pull furnace power wires through 1/2-in. (12 mm) diameter

hole in J-Box. If necessary, loosen power wires from strain--

relief wire-tie on furnace wiring harness.

4. Connect any code required external disconnect(s) to field

power wiring.

5. Route external field power wires through holes in electrical

box and casing.

6. Connect field ground wire and factory ground wire to green

ground screw on J--Box mounting bracket as shown in Fig.

30.

7. Connect field power and neutral leads to furnace power

leads as shown in Fig. 33.

8. Attach furnace J-Box cover to mounting bracket with

screws supplied in loose parts bag. Do not pinch wires

between cover and bracket.

9. Complete external disconnect wiring and installation. Con-

nect line voltage leads as shown in Fig. 31. Use best prac-

tices (NEC in U.S.A. for wire bushings, strain relief, etc.,

CANADA: Canadian Electrical Code CSA C22.1)

Power Cord Installation in Furnace J--Box

NOTE: Power cords must be able to handle the electrical

requirements listed in Table 9. Refer to power cord manufacturer’s

listings.

1. Install J--Box mounting bracket to inside of furnace casing.

(See Fig. 30.)

2. Route listed power cord through 7/8--in. (22 mm) diameter

hole in casing and J--Box bracket.

3. Secure power cord to J--Box bracket with a strain relief

bushing or a connector approved for the type of cord used.

4. Pull furnace power wires through 1/2--in. (12 mm) diameter

hole in J--Box. If necessary, loosen power wires from

strain—relief wire--tie on furnace wiring harness.

5. Connect field ground wire and factory ground wire to green

ground screw on J--Box mounting bracket as shown in Fig.

30.

6. Connect power cord power and neutral leads to furnace

power leads as shown in Fig. 33.

7. Attach furnace J--Box cover to mounting bracket with

screws supplied in loose parts bag. Do not pinch wires

between cover and bracket. (See Fig. 30).

BX Cable Installation in Furnace J--Box

1. Install J--Box mounting bracket to inside of furnace casing.

See Fig. 30.

2. Route BX connector through 7/8--in. (22 mm) diameter

hole in casing and J--Box bracket.

3. Secure BX cable to J--Box bracket with connectors ap-

proved for the type of cable used.

4. Connect field ground wire and factory ground wire to green

ground screw on J--Box mounting bracket as shown in Fig.

30.

5. Connect field power and neutral leads to furnace power

leads. as shown in Fig. 33.

6. Attach furnace J--Box cover to mounting bracket with

screws supplied in loose parts bag. Do not pinch wires

between cover and bracket.

24--V Wiring

Make field 24--v connections at the 24--v terminal strip. (See Fig.

34.) Connect terminal Y/Y2 as shown in Fig. 33 for proper cooling

operation. Use only AWG No. 18, color--coded, copper thermostat

wire.

NOTE: Use AWG No. 18 color-coded copper thermostat wire for

lengths up to 100 ft. (30.5 M). For wire lengths over 100 ft., use

AWG No. 16 wire.

The 24--v circuit contains an automotive--type, 3--amp. fuse located

on the control. Any direct shorts during installation, service, or

maintenance could cause this fuse to blow. If fuse replacement is

required, use ONLY a 3--amp. fuse of identical size. See Fig. 34.

Thermostats

For best results, use a communicating wall control to control this

modulating furnace. A single stage or two--stage heating and

cooling thermostat can be used with the furnace. The furnace

control board CPU will control the furnace and outdoor unit

staging. A two stage heating and cooling thermostat can also be

used to control the staging. However, full modulating capability

will not be available when the furnace staging is controlled by the

thermostat. Furnace staging will be limited to Minimum and

Maximum inputs or Intermediate and Maximum inputs depending

on the configuration of set-up switches SW1-2 and SW4-2. For

two stage thermostat control of a 2-stage outdoor unit, remove the

ACRDJ jumper from the furnace control board. Refer to typical

thermostat wiring diagrams and the Sequence of Operation section

for additional details. Consult the thermostat installation

instructions for specific information about configuring the

thermostat. See Fig. 34 and 35.

Accessories (See Fig. 32 and 34.)

1. Electronic Air Cleaner (EAC)

Connect an accessory Electronic Air Cleaner (if used) using

1/4--in. female quick connect terminals to the two male

1/4--in. quick--connect terminals on the control board

marked EAC--1 and EAC--2. The terminals are rated for

115VAC, 1.0 amps maximum and are energized during

blower motor operation.

59MN7A

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Carrier 59MN7A Instruction Manual Page 33

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