Carrier 38HDR Operation: CLO Board Wiring Diagram & Cooling Sequence
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LEGEND

C

— Contactor, Compressor

Splice (Field)

CAP

— Capacitor

 

CCHT

— Crankcase Heater

Terminal (Marked)

 

Thermostat

 

 

CH

— Crankcase Heater

Terminal (Unmarked)

CLO

— Compressor Lockout

 

COMP

— Compressor Motor

Terminal Block

CT

— Current Transformer

 

EQUIP

— Equipment

Splice

GND

— Ground

Factory Wiring

HPS

— High-Pressure Switch

Field Control Wiring

LPS

— Low-Pressure Switch

OFM

— Outdoor-Fan Motor

Field Power Wiring

OL

— Overload

 

TB

— Terminal Board

 

NOTES:

1.Compressor and fan motors are thermally protected.

2.Wire in accordance with National Electrical Code (NEC) and local codes. Replace any original wires with 90° C wire or its equivalent.

3.The CLO locks out the COMP to prevent short cycling on COMP overloads and safety devices. Before replacing CLO check these devices.

4.If indoor section has a transformer with a grounded secondary, connect the grounded side to “C” on the low voltage board.

5.Use minimum 60° C wire for field power wiring.

6.Crankcase heater and thermostat used on selected models only.

38HDR OPERATION SEQUENCE

CALL FOR COOLING:

1.Control voltage from transformer to thermostat (24 v).

2.At thermostat 24 v is switched to “G” and “Y.”

3.24 v from thermostat “G” energizes fan relay at indoor fan coil and indoor-fan motor runs.

4.24 v from thermostat “Y” energizes the logic in the CLO, and the contactor coil, both at the outdoor unit. Compressor and outdoor-fan motor run.

6.If the internal protector of the compressor, HPS, or LPS open, the 24 v to the contactor coil will be inter- rupted, the compressor and outdoor-fan motor will stop, and the CLO will keep the circuit open until reset by stopping and restarting the 24 v power at the thermostat.

Fig. 7 — 38HDR018-060 Typical Wiring Schematic

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Contents Installation, Start-Up Service Instructions 38HDF,HDR Unit Dimensions Rig and Mount Unit Lifting Unit with Sling38HDF018-036 Physical Data 38HDR018-060 Physical Data Unit 38HDRMake Electrical Connections Typical Control Circuit Connections38HDF Electrical Data 38HDR Electrical Data 38HDRGND CAPCcht HPSComp CLOEquip Preliminary Checks Condenser-Fan Mounting PositionsRefrigerant Charging Pressure vs. Temperature Chart Puron Refrigerant R-410A Pressure Temperature PsigLubrication Required Liquid Line Liquid Pressure Temperature FSubcooling Charging Table Troubleshooting the Cooling Cycle Copyright 2006 Carrier Corporation

38HDR018-060, 38HDF018-036 specifications

Carrier is a renowned name in HVAC technology, and their 38HDR018-060 and 38HDF018-036 models showcase the fine craftsmanship and innovation typical of the brand. These rooftop units are designed to deliver reliable heating and cooling solutions, making them an ideal choice for commercial spaces and industrial applications.

One of the main features of the Carrier 38HDR and 38HDF series is their ability to provide efficient climate control. The units are equipped with high-efficiency scroll compressors, which ensure reduced energy consumption while maintaining optimal performance. This efficiency translates into significant cost savings on energy bills, making these units an environmentally conscious choice as well.

In terms of design, the 38HDR and 38HDF models boast a rugged construction that can withstand various weather conditions. They are built with a galvanized steel cabinet that resists corrosion, ensuring durability and longevity. The compact design of these rooftop units allows for easy installation and integration into existing structures, offering flexibility for building owners and operators.

Advanced technology is at the heart of these Carrier units. The inclusion of a microprocessor-based control system enables precise temperature management and system monitoring. This technology not only optimizes performance but also provides valuable data for maintenance planning, ultimately reducing the risk of unexpected failures.

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Moreover, both series support enhanced indoor air quality features. With the option for advanced filtration systems, they can effectively remove airborne contaminants, contributing to a healthier indoor environment.

In summary, Carrier's 38HDR018-060 and 38HDF018-036 rooftop units are a powerful combination of efficiency, durability, and advanced technology. Their ability to provide customized heating and cooling solutions makes them an excellent investment for any commercial or industrial application, ensuring comfort and performance for years to come.
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