Cooling and Heating Troubleshooting Chart (cont'd)

SYMPTOM

CAUSE

REMEDY

Suction pressure too low

(Cool) Dirty air filter

Replace filter

 

 

 

 

(Heat) Outdoor coil frosted

Move timer on control board to 30 min. between

 

defrost cycles

 

 

 

 

 

 

Low refrigerant charge

Check for leaks, repair and recharge

 

 

 

 

Metering device or low side restricted

Remove source of restriction

 

(Cool) Insufficient coil airflow

Increase air quantity

 

Check filterÐreplace if necessary

 

 

 

(Cool) Temperature too low in conditioned area

Reset thermostat

 

 

 

 

(Cool) Outdoor ambient below 40°F

Install low-ambient kit

 

 

 

 

Field-installed filter-drier restricted

Replace

Compressor runs but outdoor fan does not

NC (normally closed) contacts on defrost board

Check condition of relay on board

open

Replace if necessary

 

IFM does not run

Blower wheel not secured to shaft

Properly tighten blower wheel to shaft

 

Insufficient voltage at motor

Determine cause and correct

 

 

 

 

Power connectors not properly sealed

Connectors should snap easily; do not force

 

 

 

 

Motor programmed with a delay profile

Allow a few min. for motor to shut off

IFM runs when it should be off

With thermostat in off state, the voltage on G,

If measured voltage is more than 1/2, the ther-

Y1,Y, Y2, W with respect to common, should be

mostat is incompatible with motor

 

 

1/2 of actual low voltage supply

If voltage is less than 1/2, the motor has failed

 

 

 

 

Water dripping into motor

Verify proper drip loops in connector wires

IFM operation is intermittent

Connectors not firmly sealed

Gently pull wires individually to be sure they are

 

crimped into the housing

 

 

 

 

 

IFMÐIndoor Fan Motor

 

 

 

START-UP CHECKLIST

 

 

(REMOVE AND STORE IN JOB FILE)

 

I. PRELIMINARY INFORMATION

 

 

Model No

 

 

Serial No

 

 

Date

 

 

Technician

 

 

II.PRE-START-UP

___ Verify that all packing materials have been removed from unit

___ Remove all shipping holddown bolts and brackets per installation instructions

___ Verify that condensate connection is installed per installation instructions

___ Check all electrical connections and terminals for tightness

___ Check that indoor (evaporator) air filter is clean and in place

___ Verify that unit installation is level

___ Check fan wheel and propeller for location in housing and setscrew tightness

III. START-UP

Supply Voltage: L1-L2 __________ L2-L3 _________ L3-L1 __________

Compressor Amps: L1 __________ L2 _________ L3 __________

Indoor Fan Amps: __________

TEMPERATURE

Outdoor-Air Temperature: __________ DB

Return-Air Temperature: __________ DB __________ WB

Heat Pump Supply Air: __________

Electric Heater Supply Air: __________

PRESSURES

Refrigerant Suction __________ psig

Refrigerant Discharge __________ psig

___ Verify refrigerant charge using charging tables

___ Verify 3-phase scroll compressor is rotating in correct direction

25

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Carrier 50JS Cooling and Heating Troubleshooting Chart contd, START-UP Checklist Remove and Store in JOB File

50JS specifications

The Carrier 50JS is a high-performance rooftop unit designed for commercial applications, combining advanced technology with energy efficiency to deliver optimal heating and cooling performance. Its compact design allows for easy installation, making it an ideal choice for various settings such as retail spaces, schools, and office buildings.

One of the standout features of the Carrier 50JS is its innovative energy efficiency. Equipped with a high-efficiency scroll compressor, it significantly reduces energy consumption while providing reliable climate control. This model boasts a commendable SEER (Seasonal Energy Efficiency Ratio) rating, which translates to lower utility bills and a reduced carbon footprint, meeting modern energy efficiency standards.

The 50JS unit utilizes R-410A refrigerant, an environmentally friendly option that contributes to its low global warming potential compared to traditional refrigerants. This aligns with Carrier's commitment to sustainability and reducing environmental impact.

Another significant characteristic of the 50JS is its advanced controls and intelligent building integration capabilities. The unit comes with a microprocessor-based control system that allows for precise temperature management and can be easily integrated into building automation systems. This feature enhances user experience, providing real-time data and better management of HVAC operations.

Noise reduction technology is also a key design focus of the Carrier 50JS. The unit incorporates sound-attenuating materials and features that minimize operational noise, making it suitable for noise-sensitive environments like offices and educational institutions.

In terms of air quality, the 50JS offers various filtration options, including high-efficiency filters that remove airborne particulates. This results in cleaner, healthier indoor air, which is crucial for occupant comfort and well-being.

Furthermore, the rooftop unit is built to withstand harsh weather conditions, featuring a durable cabinet constructed from galvanized steel with a corrosion-resistant finish. This enhances the unit's longevity and reliability over time.

In conclusion, the Carrier 50JS rooftop unit stands out in the commercial HVAC market due to its energy efficiency, advanced controls, quiet operation, and robust design. It represents a blend of state-of-the-art technology and practical features, making it a preferred choice for those looking to invest in reliable and sustainable climate control solutions.