Carrier 38CKS, Product Data

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Accessory description and usage (continued)
5. Crankcase Heater
An electric resistance heater which mounts to the base of the compressor to keep the lubricant warm during off cycles. Improves compressor lubrication on
restart and minimizes the chance of liquid slugging.
Usage Guideline:
Required in low ambient applications.
Required in long line applications.
Suggested in all commercial applications.
6. Evaporator Freeze Thermostat
An SPST temperature-actuated switch that stops unit operation when evaporator reaches freeze-up conditions.
Usage Guideline:
Required when low ambient kit has been added.
7. Filter Drier—Bi-Flow
A device for removing contaminants from refrigerant circulating in an air conditioning system: single-direction flow.
Usage Guideline:
Suggested in all field-connected split-system air conditioners.
8. High-Pressure Switch
Auto reset SPST switch activated by refrigerant pressure on high side of refrigerant circuit. Cycles compressor off if refrigerant pressure rises to 426 ± 10 psig
and resets at 320 ± 20 psig. Provides protection against compressor damage due to loss of outdoor airflow.
Usage Guideline:
Suggested in installations exposed to "very dirty" outdoor air.
Suggested in installations where condenser inlet air temperature exceeds 125°F. (51.7°C)
9. Liquid-Line Solenoid Valve (LLS)
This device serves two purposes. It is an electrically operated shutoff valve which stops and starts refrigerant liquid flow in response to compressor operation.
It maintains a column of refrigerant liquid ready for action at next compressor operation cycle. It also provides system protection against off-cycle refrigerant
migration.
NOTE: When LLS is used with reciprocating compressors, Compressor Start Assist — Capacitor and Relay is required.
Usage Guideline:
Required in air conditioner long line applications with a piston indoor metering device to prevent off cycle refrigerant migration. A hard shut
off TXV can be used instead of LLS in single flow air conditioner applications. See Long Line Application Guideline.
10. Low-Ambient Pressure Switch
A long life pressure switch which is mounted to outdoor unit service valve. It is designed to cycle the outdoor fan motor in order to maintain head pressure
within normal operating limits (approximately 100 psig to 225 psig). The control will maintain working head pressure at low-ambient temperatures down to 0°F
(–17.8°C) when properly installed.
Usage Guideline:
A Low-Ambient Pressure Switch or Motor Master ®—Low-Ambient Controller must be used when cooling operation is used at outdoor tem-
peratures below 55°F (12.8°C).
11. MotorMaster®-Low-Ambient Controller
A fan speed control device activated by a temperature sensor, designed to control condenser fan motor speed in response to the saturated, condensing temperature
during operation in cooling mode only. For outdoor temperatures down to –20°F (–28.9°C), it maintains condensing temperature at 100°F ± 10°F (37.8°C ± –
12°C).
Usage Guideline:
A Motor Master ®—Low-Ambient Controller or Low-Ambient Pressure Switch must be used when cooling operation is used at outdoor tem-
peratures below 55°F (12.8°C).
Suggested for all commercial applications.
12. Outdoor Air Temperature Sensor
Designed for use with Carrier Thermostats listed in this publication. The device enables the thermostat to display the outdoor temperature. This device also is
required to enable special thermostat features such as auxiliary heat lock out.
Usage Guideline:
Suggested for all Carrier thermostats listed in this publication.
13. Sound Hood
Wraparound sound reducing cover for the compressor. Reduces the sound level by about 2 dBA.
Usage Guideline:
Suggested when unit is installed closer than 15 ft to quiet areas—bedrooms, etc.
Suggested when unit is installed between two houses less than 10 ft apart.
14. Thermostatic Expansion Valve (TXV) Single-Flow
A modulating flow-control valve which meters refrigerant liquid flow rate into the evaporator in response to the superheat of the refrigerant gas leaving the
evaporator. Kit includes valve, adapter tubes, and external equalizer tube. Both hard shutoff and RPB valves are available.
NOTE: When using a hard shut off TXV with single phase reciprocating compressors, a Compressor Start Assist — Capacitor and Relay is required.
Usage Guideline:
Required to achieve ARI ratings in certain equipment combinations. Refer to combination ratings.
Hard shut off TXV or LLS required in air conditioner long line applications.
Required for use on all zoning systems.
15. Time-Delay Relay
An SPST delay relay which briefly continues operation of indoor blower motor to provide additional cooling after the compressor cycles off.
NOTE: Most indoor unit controls include this feature. For those that do not, use the guideline below.
Usage Guideline:
For improved efficiency ratings for certain combinations of indoor and outdoor units. Refer to ARI Unitary Directory.