Table 5ÐCooling and Heating Troubleshooting Chart

SYMPTOM

CAUSE

REMEDY

 

Power failure

Call power company

 

 

 

 

Fuse blown or circuit breaker tripped

Replace fuse or reset circuit breaker

 

 

 

 

Defective thermostat, contactor, transformer, con-

Replace component

 

trol relay or defrost board

 

 

 

 

 

Compressor and outdoor fan will not start

Insufficient line voltage

Determine cause and correct

Incorrect or faulty wiring

Check wiring diagram and rewire correctly

 

 

 

 

 

Thermostat setting too high

Lower thermostat setting below room tempera-

 

ture

 

 

 

 

 

 

 

DO NOT bypass this compressor time

 

Units have a 5-min. time delay

delayÐwait for 5 min. until time-delay relay is

 

 

deenergized

 

Faulty wiring or loose connections in compressor

Check wiring and repair or replace

 

circuit

 

 

 

 

 

 

Compressor motor burned out, seized, or internal

Determine cause

Compressor will not start but condenser fan

overload open

Replace compressor

 

 

Defective run capacitor, overload, or PTC (posi-

 

runs

Determine cause and replace

tive temperature coefficient) thermistor

 

 

 

 

 

 

One leg of 3-phase power dead

Replace fuse or reset circuit breaker

 

Determine cause

 

 

 

 

 

 

Low input voltage (20% low)

Determine cause and correct

Three-phase scroll compressor (size 030-

Scroll compressor is rotating in the wrong direc-

Correct the direction of rotation by reversing the

060units) makes excessive noise, and there

tion

3-phase power leads to the unit

may be a low pressure differential

 

 

 

 

 

 

Refrigerant overcharge or undercharge

Recover refrigerant, evacuate system, and re-

 

charge to capacities shown on nameplate

 

 

 

 

 

 

Defective compressor

Replace and determine cause

 

Insufficient line voltage

Determine cause and correct

Compressor cycles (other than normally sat-

Blocked outdoor coil

Determine cause and correct

 

 

Defective run/start capacitor, overload or start

 

isfying thermostat)

Determine cause and replace

relay

 

 

 

 

 

 

Defective thermostat

Replace thermostat

 

 

 

 

Faulty outdoor-fan motor or capacitor

Replace

 

Damaged reversing valve

Determine cause and correct

 

 

 

 

Restriction in refrigerant system

Locate restriction and remove

 

 

 

 

Dirty air filter

Replace filter

 

Unit undersized for load

Decrease load or increase unit size

 

Thermostat set too low

Reset thermostat

 

 

 

 

Low refrigerant charge

Locate leak, repair, and recharge

 

Leaking valves in compressor

Replace compressor

Compressor operates continuously

 

Check defrost time settings

 

Frosted coil with incorrect defrost operation

Reset as necessary

 

Check defrost temperature switch

 

 

 

 

Replace as necessary

 

 

 

 

Air in system

Recover refrigerant, evacuate system, and re-

 

charge

 

 

 

 

 

 

Outdoor coil dirty or restricted

Clean coil or remove restriction

 

 

 

 

Dirty air filter

Replace filter

 

Dirty indoor or outdoor coil

Clean coil

 

Refrigerant overcharged

Recover excess refrigerant

Excessive head pressure

 

 

Air in system

Recover refrigerant, evacuate system, and re-

 

charge

 

 

 

 

 

 

(Heat) Indoor air restricted or recirculating

Determine cause and correct

 

 

 

 

Indoor or outdoor air restricted or air short-cycling

Determine cause and correct

 

Low refrigerant charge

Check for leaks, repair and recharge

Head pressure too low

 

 

Compressor valves leaking

Replace compressor

 

 

 

 

Restriction in liquid tube

Remove restriction

 

(Heat) Outdoor coil frosted

Move timer on control board to 30 min. between

 

defrost cycles

 

 

Excessive suction pressure

(Cool) High Heat load

Check for source and eliminate

Compressor valves leaking

Replace compressor

 

 

 

 

 

Reversing valve hung up or leaking internally

Replace valve

 

Refrigerant overcharged

Recover excess refrigerant

 

 

 

24

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Carrier 50JS instruction manual ÐCooling and Heating Troubleshooting Chart, Symptom Cause Remedy
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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.
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