Carrier 48/50AJ specifications Start-Up

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 installation 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 routed to the supply ducts as required.

Accessory Installation — Check to make sure that all accessories including space thermostats 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 compres- sors are running.

IMPORTANT: Unit power must be on for 24 hrs prior to start-up of compressors. Otherwise damage to com- pressors may result.

Evaporator Fan — Fan belt and fixed pulleys are factory- installed. See Tables 3-38 for fan performance. Remove tape from fan pulley, and be sure that fans rotate in the proper direc- tion. See Table 39 for motor limitations. See Tables 40A and 40B for air quantity limits. Static pressure drop for power exhaust is negligible. To alter fan performance, see Evaporator Fan Performance Adjustment section on page 130.

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 Disable (Service Test→STOP) to No.

1.Set any control configurations that are required (field- installed accessories, etc.). The unit is factory configured for all appropriate factory-installed options.

2.Enter unit set points. The unit is shipped with the set point default values. If a different set point is required use the scrolling marquee, Navigator™ accessory or Service Tool software to change the configuration valves.

3.If the internal unit schedules are going to be used config- ure the Occupancy schedule.

4.Verify that the control time periods programmed meet current 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 set point 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 incoming 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.

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