REMEDY/

CONDITION

POSSIBLE CAUSE

REFERENCE

 

 

SECTION

5.6 UNIT WILL NOT DEFROST PROPERLY -- Continued

 

 

 

 

Will not initiate defrost

Manual defrost switch defective

Replace

manually

Defrost temperature sensor open

4.9.5

 

 

 

Initiates but relay (DR) drops

Low line voltage

2.3

out

 

 

Initiates but does not defrost

Heater contactor or coil defective

Replace

 

 

Heater(s) burned out

6.15

 

 

 

 

Frequent defrost

Wet load

Normal

 

 

 

5.7 ABNORMAL PRESSURES (COOLING)

 

 

 

 

 

Condenser coil dirty

6.11

 

 

 

 

Condenser fan rotating backwards

6.12

High discharge pressure

Condenser fan inoperative

6.12

 

 

Refrigerant overcharge or noncondensibles

6.7.1

 

 

Discharge service valve partially closed

Open

 

 

 

 

Suction modulation valve malfunction

6.20

 

 

 

 

Faulty suction pressure transducer

Replace

 

 

 

 

Suction service valve partially closed

Open

 

 

 

 

Filter-drier partially plugged

6.13

 

 

 

 

Low refrigerant charge

6.7.1

 

 

 

Low suction pressure

Expansion valve defective

6.14

 

No evaporator air flow or restricted air flow

6.15

 

 

 

 

Excessive frost on evaporator coil

5.6

 

 

 

 

Evaporator fan(s) rotating backwards

2.3

 

 

 

 

Suction modulation valve malfunction

6.20

 

 

 

Suction and discharge pressures

Compressor operating in reverse

5.14

tend to equalize when unit is

 

 

Compressor cycling/stopped

Check

operating

 

 

 

5.8 ABNORMAL NOISE OR VIBRATIONS

 

 

 

 

 

Compressor start up after an extended shutdown

Normal

 

 

 

Brief chattering when manually shut down

 

 

 

 

 

 

Compressor operating in reverse

5.14

Compressor

Loose mounting bolts or worn resilient mounts

Tighten/Replace

 

Loose upper mounting

6.8.1 step r.

 

Liquid slugging

6.14

 

 

 

 

Insufficient oil

6.9

 

Bent, loose or striking venturi

Check

 

 

 

Condenser or Evaporator Fan

Worn motor bearings

6.12/6.17

 

Bent motor shaft

6.12/6.17

 

 

 

5-3

T-309

Page 62
Image 62
Carrier 69NT20-531-300 manual Will not initiate defrost, Bent motor shaft

69NT20-531-300 specifications

The Carrier 69NT20-531-300 is a cutting-edge rooftop unit designed to meet the demanding requirements of commercial heating and cooling applications. This model embodies Carrier’s commitment to energy efficiency, reliability, and advanced technological features that enhance indoor comfort while minimizing operational costs.

One of the standout features of the Carrier 69NT20-531-300 is its high energy efficiency. It is equipped with advanced compressor technology that optimizes performance while reducing energy consumption. This ensures that businesses can maintain a comfortable indoor climate without incurring exorbitant utility bills. With a high Seasonal Energy Efficiency Ratio (SEER) and Energy Efficiency Ratio (EER), users can expect not only enhanced comfort but also significant cost savings over time.

The cooling capabilities of the 69NT20-531-300 are complemented by its robust heating options. This unit utilizes a gas heat exchanger, ensuring quick and even heating throughout the space. The combination of cooling and heating capabilities in one compact unit makes it a versatile choice for various applications, including retail spaces, offices, and warehouses.

In addition to its impressive performance specifications, the Carrier 69NT20-531-300 incorporates innovative technologies that further enhance its functionality. The unit comes with advanced controls, allowing for precise temperature regulation and zoning capabilities. This ensures that different areas of a building can maintain their desired temperatures based on usage, improving overall energy efficiency.

Durability is another hallmark of the Carrier 69NT20-531-300. The unit is constructed with high-quality materials and features a weather-proof cabinet that protects it from the elements, ensuring long-term reliability even in harsh conditions. Furthermore, its modular design simplifies maintenance, making it easy for technicians to access critical components.

The 69NT20-531-300 is also designed with low noise operation in mind. It employs sound-dampening technology to ensure that operations are quiet, making it an ideal choice for locations where noise reduction is a priority, such as schools or healthcare facilities.

Overall, the Carrier 69NT20-531-300 stands out as a premier choice for businesses looking for an efficient, reliable, and feature-rich rooftop HVAC unit. Its blend of energy efficiency, advanced technology, and durability positions it as a leader in commercial heating and cooling solutions, making it a valuable investment for any commercial property.