Carrier 38YSA instruction manual LinePower Connections, Start-Up, CompressorCrankcase Heater

The unit cabinet must have an uninterrupted or unbroken ground to minimize personal injury if an electrical fault should occur. The ground may consist of electrical wire or metal conduit when installed in accordance with existing electrical codes. Failure to follow this warning can result in an electric shock, fire, or death.

CONNECT GROUND AND POWER WIRES

Connect ground wire to ground connection in control box for safety. Connect power wiring to contactor as shown in Fig.8.

Step 12—Start-Up

To prevent compressor damage or personal injury, observe the following:

•Do not overcharge system with refrigerant.

•Do not operate unit in a vacuum or at negative pressure.

•Do not disable low-pressure switch.

In scroll compressor applications:

• Dome temperatures may be hot.

DISCONNECT

PER N. E. C. AND/OR LOCAL CODES

FIELD POWER

WIRING

FIELD GROUND

WIRING

CONTACTOR

GROUND

LUG

A91056

To prevent personal injury wear safety glasses, protective clothing, and gloves when handling refrigerant and observe the following:

•Back seating service valves are not equipped with Schrader valves. Fully back seat (counter clockwise) valve stem before removing gage port cap.

Do not vent refrigerant to atmosphere. Recover during system repair or final unit disposal.

Follow these steps to properly pumpdown a system and avoid

Fig. 8—Line Power Connections

CONNECT CONTROL WIRING

Route 24-v control wires through control wiring grommet and connect leads to control wiring. (See Fig. 9-13.)

Use No. 18 AWG color-coded, insulated (35°C minimum) wire. If thermostat is located more than 10 ft from unit, as measured along the control voltage wires, use No. 16 AWG color-coded wire to avoid excessive voltage drop.

All wiring must be NEC Class 1 and must be separated from incoming power leads.

Use furnace transformer, fan coil transformer, or accessory trans- former for control power, 24-v/40-va minimum.

NOTE: Use of available 24-v accessories may exceed the mini- mum 40-va power requirement. Determine total transformer load- ing and increase the transformer capacity or split the load with an accessory transformer as required.

IMPORTANT: Check factory wiring and wire connections to ensure terminations are secured properly. Check wire routing to ensure wires are not in contact with tubing, sheet metal, etc.

Step 10—Compressor Crankcase Heater

When equipped with a crankcase heater, furnish power to heater a minimum of 24 hr before starting unit. To furnish power to heater only, set thermostat to OFF and close electrical disconnect to outdoor unit.

A crankcase heater is required if refrigerant tubing is longer than 50 ft.

Step 11—Install Electrical Accessories

Refer to the individual instructions packaged with kits or acces- sories when installing.

negative suction pressure.

1.Fully back seat (open) liquid and vapor tube service valves.

2.Unit is shipped with valve stem(s) front seated (closed) and caps installed. Replace stem caps after system is opened to refrigerant flow. Replace caps finger-tight and tighten with wrench an additional 1/12 turn. Use a backup wrench on valve body flats to prevent distortion of sheet metal.

3.Close electrical disconnects to energize system.

4.Set room thermostat to desired temperature. Be sure set point is below indoor ambient temperature.

5.Set room thermostat to HEAT or COOL and fan control to ON or AUTO mode, as desired. Operate unit for 15 minutes. Check system refrigerant charge.

SEQUENCE OF OPERATION

NOTE: Defrost control board is equipped with 5-minute lockout timer which may be initiated upon any interruption of power.

With power supplied to indoor and outdoor units, transformer is energized.

Cooling

On a call for cooling, thermostat makes circuits R-O, R-Y, and R-G. Circuit R-O energizes reversing valve, switching it to cooling position. Circuit R-Y energizes contactor, starting outdoor fan motor and compressor circuit. R-G energizes indoor unit blower relay, starting indoor blower motor on high speed.

When thermostat is satisfied, its contacts open, de-energizing the contactor and blower relay. Compressor and motors should stop.

NOTE: If indoor unit is equipped with a time-delay relay circuit, the blower runs an additional 90 sec to increase system efficiency.

Heating

On a call for heating, thermostat makes circuits R-Y and R-G. Circuit R-Y energizes contactor, starting outdoor fan motor and compressor. Circuit R-G energizes indoor blower relay, starting blower motor on high speed.

Should temperature continue to fall, R-W2 is made through second-stage room thermostat bulb. Circuit R-W2 energizes a sequencer, bringing on first bank of supplemental electric heat and

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