Carrier 38BYG, 38BYC instruction manual Accessory Usage, Start-Up, Compressor Crankcase Heater

Table 2—Accessory Usage

	REQUIRED FOR	REQUIRED FOR	REQUIRED FOR
ACCESSORY	LOW-AMBIENT	LONG-LINE	BURIED LINE
	APPLICATIONS	APPLICATIONS*	APPLICATIONS†
	(BELOW 55°F)	(OVER 50 FT)	(OVER 3 FT)
Crankcase Heater	Yes	Yes	Yes
Evaporator Freeze Thermostat	Yes	No	No
Accumulator	No	No	Yes
Compressor Start-Assist	Yes	Yes	Yes
Capacitor and Relay
MotorMaster® Control,
or	Yes	No	No
Low-Ambient Pressure Switch
Wind Baffle	See low-ambient	No	No
	Instructions
Unit Risers	Recommended	No	No
Liquid-Line Solenoid Valve		See Long-Line
or	No	Application	Yes
Hard-Shutoff TXV		Guideline
Ball-Bearing Fan Motor	Yes‡	No	No

*For tubing line sets between 50 and 175 ft, refer to Application Guideline and Service Manual — Air Conditioners and Heat Pumps.

† For buried line applications, refer to Application Guideline and Service Manual — Air Conditioners and Heat Pumps.

‡ Required for low-ambient controller (full-modulation feature) and MotorMaster® Control only.

DISCONNECT

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

FIELD POWER

WIRING

FIELD GROUND

WIRING

CONTACTOR

GROUND

LUG

A91056

Step 13—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.

Fig. 8—Line Power Connections

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

NOTE: Use of available 24v accessories may exceed the mini- mum 40va 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, and so forth.

Step 11—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 12—Install Electrical Accessories

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

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 (counterclockwise) valve stem before removing gage-port cap.

•Front-seating service valves are equipped with Schrader valves.

Federal Regulations require that you do not vent refrigerant to atmosphere. Recover during system repair or final unit disposal.

Follow these steps to properly pumpdown a system and avoid 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.

3.Close electrical disconnects to energize system.

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