Start-Up; Unit Preparation; Unit Setup; Internal Wiring - Carrier WeatherMaker 48A2020 Controls, Start-Up, Operation, Service And Troubleshooting Instructions

START-UP

IMPORTANT: Do not attempt to start unit, even
momentarily, until all items on the Start-Up Checklist
and the following steps have been completed.

Unit Preparation

Check that unit has been installed in accordance with the in-
stallation instructions and applicable codes.

Unit Setup

Make sure that the economizer hoods have been installed and
that the outdoor filters are properly installed.

Internal Wiring

Ensure that all electrical connections in the control box are
tightened as required. If the unit has staged gas heat make sure
that the leaving air temperature (LAT) sensors have been rout-
ed to the supply ducts as required.

Accessory Installation

Check to make sure that all accessories including space ther-
mostats and sensors have been installed and wired as required
by the instructions and unit wiring diagrams.

Crankcase Heaters

Crankcase heaters are energized as long as there is power to the
unit, except when the compressors are running.
IMPORTANT: Unit power must be on for 24 hours
prior to start-up of compressors. Otherwise damage to
compressors may result.

Evaporator Fan

Fan belt and fixed pulleys are factory-installed. See Tables 3-
26 for fan performance. Remove tape from fan pulley, and be
sure that fans rotate in the proper direction. See Table 27 for
motor limitations. See Tables 28 and 29 for air quantity limits.
Static pressure drop for power exhaust is negligible. To alter
fan performance, see Evaporator Fan Performance Adjustment
section on page 139.

Controls

Use the following steps for the controls:
IMPORTANT: The unit is shipped with the unit control
disabled. To enable the control, set Local Machine Dis-

able (Service Test STOP) to No.
1. Set any control configurations that are required (field- in-
stalled accessories, etc.). The unit is factory configured for
all appropriate factory-installed options.
2. Enter unit setpoints. The unit is shipped with the setpoint de-
fault values. If a different setpoint is required use the scroll-
ing marquee, Navigator™ accessory or Service Tool soft-
ware to change the configuration valves.
3. If the internal unit schedules are going to be used configure
the Occupancy schedule.
4. Verify that the control time periods programmed meet cur-
rent requirements.
5. Using Service Test mode, verify operation of all major
components.
6. If the unit is a VAV unit make sure to configure the VFD
static pressure setpoint using the display. To checkout the
VFD use the VFD instructions shipped with the unit.

Gas Heat

Verify gas pressure before turning on gas heat as follows:
1. Turn off field-supplied manual gas stop, located external to
the unit.
2. Connect pressure gages to supply gas tap, located at field-
supplied manual shutoff valves.
3. Connect pressure gages to manifold pressure tap on unit gas
valve.
4. Supply gas pressure must not exceed 13.5 in. wg. Check
pressure at field-supplied shut-off valve.
5. Turn on manual gas stop and initiate a heating demand.
Jumper R to W1 in the control box to initiate heat.
6. Use the Service Test procedure to verify heat operation.
7. After the unit has run for several minutes, verify that incom-
ing pressure is 6.0 in. wg or greater and that the manifold
pressure is 3.5 in wg. If manifold pressure must be adjusted
refer to Gas Valve Adjustment section on page 149.
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