Carrier 38YSA DefrostThermostat Location, Positioningof Sensing Bulb, ThermostaticExpansion Valve

Step 6—Thermostatic Expansion Valve

For proper unit operation and reliability, units must be installed with field-supplied hard shutoff TXV. Do not install with evaporator coils having capillary tube metering devices or pistons.

FEEDER TUBE

STUB TUBE

Due to system design, this unit must be installed with a factory-listed indoor section. Non-approved coils could cause performance and reliability problems. Refer to pre-sale litera- ture for approved indoor sections.

The outdoor section is factory equipped with a hard shut-off TXV for metering refrigerant during heating mode. See Fig. 5 and 6 for location of TXV and sensing bulb. This heat pump must be matched with an approved indoor fan coil equipped with a hard shut-off TXV. See Product Data literature for approved indoor units.

Step 7—Check Defrost Thermostat

Check defrost thermostat to ensure it is properly located and securely attached. There is a liquid header with a brass distributor and feeder tube going into outdoor coil. At the end of 1 of the feeder tubes, there is a 3/8-in. O.D. stub tube approximately 3 in. long. (See Fig. 7.) The defrost thermostat should be located on stub tube. Note that there is only 1 stub tube used with liquid header, and on most units it is the bottom circuit.

Step 8—Make Piping Connections

Relieve pressure and recover all refrigerant before system repair or final unit disposal to avoid personal injury or death. Use all service ports and open all flow-control devices, including solenoid valves.

DEFROST

THERMOSTAT

A97517

Fig. 7—Defrost Thermostat Location

If ANY refrigerant tubing is buried, provide a 6 in. vertical rise at service valve. Refrigerant tubing lengths up to 36 in. may be buried without further special consideration. For lengths above 36 in., consult your local distributor.

To prevent damage to unit or service valves observe the following:

•Use a brazing shield.

•Wrap service valves with wet cloth or use a heat sink material.

Outdoor units may be connected to indoor section using accessory tubing package or field-supplied refrigerant grade tubing of correct size and condition. For tubing requirements beyond 50 ft, substan- tial capacity and performance losses can occur. Following the recommendations in the Residential Split System Long-Line Application Guideline will reduce these losses. Refer to Table 1 for field tubing equivalent line length. Refer to Table 2 for accessory requirements.

SENSING BULB

DISCHARGE

MUFFLER

10 O'CLOCK

2 O'CLOCK

SENSING BULB

STRAP

SUCTION TUBE

8 O'CLOCK	4 O'CLOCK
7⁄8 IN. OD & SMALLER	LARGER THAN 7⁄8 IN. OD	STRAINER	TXV
	A81032		A96433
Fig. 5—Positioning of Sensing Bulb		Fig. 6—TXV Location on Outdoor Section

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