Carrier 50VT-A Check for Refrigerant Leaks, Start-UpAdjustments, Pre-Start-Up, 50VT--A

PRE-START-UP

!WARNING

FIRE, EXPLOSION, ELECTRICAL SHOCK AND ENVIRONMENTAL HAZARD

Failure to follow this warning could result in personal injury, death or property damage.

1.Follow recognized safety practices and wear protective goggles when checking or servicing refrigerant system.

2.Relieve and recover all refrigerant from system before touching or disturbing compressor plug if refrigerant leak is suspected around compressor terminals.

3.Do not remove compressor plug until all electrical sources are disconnected and tagged.

4.Never attempt to repair soldered connection while refrigerant system is under pressure.

5.Do not use torch to remove any component. System contains oil and refrigerant under pressure.

To remove a component, wear protective goggles and proceed as follows:

a.Shut off electrical power to unit and install lockout tag.

b.Relieve and reclaim all refrigerant from system using both high- and low-pressure ports.

c.Cut component connecting tubing with tubing cutter and remove component from unit.

d.Carefully unsweat remaining tubing stubs when necessary. Oil can ignite when exposed to torch flame.

Use the Start-Up Checklist supplied at the end of this book and proceed as follows to inspect and prepare the unit for initial start-up:

1.Remove all access panels (see Fig. 21).

2.Read and follow instructions on all DANGER, WARNING, CAUTION, and INFORMATION labels attached to, or shipped with, unit.

3.Make the following inspections:

a.Inspect for shipping and handling damages such as broken lines, loose parts, disconnected wires, etc.

b.Inspect for oil at all refrigerant tubing connections and on unit base. Detecting oil generally indicates a refrigerant leak. Leak-test all refrigerant tubing connections using electronic leak detector, or liquid-soap solution. If a refrigerant leak is detected, see following Check for Refrigerant Leaks section.

c.Inspect all field and factory-wiring connections. Be sure that connections are completed and tight. Ensure wires do not touch refrigerant tubing or sharp sheet metal edges.

d.Inspect coil fins. If damaged during shipping and handling, carefully straighten fins with a fin comb.

4.Verify the following conditions:

a.Make sure that outdoor-fan blade is correctly positioned in fan orifice.

b.Make sure that air filter(s) is in place.

c.Make sure that condensate drain pan and trap are filled with water to ensure proper drainage.

d.Make sure that all tools and miscellaneous loose parts have been removed.

5.Each unit system has 2 Schrader-type ports, one low-side Schrader fitting located on the suction line, and one

high-side Schrader fitting located on the compressor discharge line. Be sure that caps on the ports are tight.

START-UP

Checking Cooling and Heating Control Operation

Start and check the unit for proper control operation as follows: (1.) Place room thermostat SYSTEM switch or MODE

control in OFF position. Observe that blower motor starts when FAN mode is placed in FAN ON position and shuts down when FAN MODE switch is placed in AUTO position.

(2.) Thermostat:

When the room temperature rises to a point that is slightly above the cooling control setting of the thermostat, the thermostat completes the circuit between thermostat terminal R to terminals Y, O and G.These completed circuits through the thermostat connect contactor coil (C) (through unit wire Y) and Indoor Fan board (through unit wire

G)across the 24-v. secondary of transformer (TRAN).

(3.) Place system switch or MODE control in HEAT position. Set control above room temperature. Observe that compressor, outdoor fan, and indoor blower motors start. Observe that heating cycle shuts down when control setting is satisfied.

(4.) When using an automatic changeover room thermostat place both SYSTEM or MODE control and FAN mode switches in AUTO positions. Observe that unit operates in Cooling mode when temperature control is set to “call for Cooling” (below room temperature), and unit operates in Heating mode when temperature control is set to “call for Heating” (above room temperature).

NOTE: Once the compressor has started and then has stopped, it should not be started again until 5 minutes have elapsed. The defrost board has a built-in 5 minute delay between cycles. The 5 minute compressor delay also applies to heat pump heating mode.

Step 1 — Check for Refrigerant Leaks

Proceed as follows to locate and repair a refrigerant leak and to charge the unit:

1.Locate leak and make sure that refrigerant system pressure has been relieved and reclaimed from both high- and low-pressure ports.

2.Repair leak following Refrigerant Service procedures.

NOTE: Install a bi-flow filter drier whenever the system has been opened for repair.

3.Add a small charge of R-410A refrigerant vapor to system and leak-test unit.

4.Recover refrigerant from refrigerant system and evacuate to 500 microns if no additional leaks are not found.

5.Charge unit with Puron (R-410A) refrigerant, using an electronic scale. Refer to unit rating plate for required charge.

Step 2 — Start-Up Adjustments

Complete the required procedures given in the Pre-Start-Up section before starting the unit. Do not jumper any safety devices when operating the unit. Do not operate the unit in Cooling mode when the outdoor temperature is below 40_F (4_C) (unless accessory low-ambient kit is installed).

IMPORTANT: Three-phase, scroll compressors are direction oriented. Unit must be checked to ensure proper compressor 3-phase power lead orientation. If not corrected within 5 minutes, the internal protector will shut off the compressor. The 3-phase power leads to the unit must be reversed to correct rotation. When

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