Fedders R407C service manual XI. Device Protection Measures

Models: R407C

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XI. Device Protection Measures

1.3-minutes compressor switch on delay

The compressor is not switched on again for 3-minutes every time after it is switched off to protect it. This restriction applies throughout the operation of the Air-con except on power- up.

2.Cool mode protection (Low-pressure indicator)

If the indoor coil thermistor temperature is 25°C and above after the compressor has been turned on for more than 30 minutes in cool mode only, the compressor stop, outdoor fan stop, 4-way valve off and indoor fan run at low speed and the RED LED will blink at 95 times per minute.

When compressor is stopping , the microprocessor will not monitoring the indoor coil thermistor temperature

(applicable on Heat Pump Unit only)

If the outdoor coil thermistor temperature is more than 60°C in cool mode, the compressor stops, the outdoor fan remains on, 4-way valve remains off, indoor fan run at set speed.

If the outdoor coil thermistor temperature later dips to 50°C or below in cool mode, the compressor on, outdoor fan remain on, 4-way valve remain off, indoor fan run at set speed.

3.Heat mode protection (applicable on Heat Pump Unit only)

If the indoor coil thermisor temperature is 28°C and below after the compressor has been turned on for more than 30 minutes in heat mode only, then the compressor will stop and the outdoor fan will stop, the 4-way valve will remain on and the indoor fan stop, the RED LED will blink at 95 times per minute.

The thermistor accuracy and responses time both are very critical for heat mode indoor coil overload protection, The software must be able to detect the system rate of change, this would allow the unit to operate at very exrtrem condition without stopping or tripping the compressor during the heat mode operation. Details refer to Heat Mode Protection Control Sequences attached.

4.On/off Hysteresis

In order to avoid switching the relays and the associated devices too frequently, some hysteresis is incorporated into the starting and stopping of the operation cycles.

In the cool, heat and dry modes, the respective cycles start and stop as shown in the diagram below:

Room temperature

< Set pt-1°C

= Set pt-1°C

= Set pt.

= Set pt+1°C

> Set pt+1°C

Cycle

Stop

Stop

*

Start

Start

*Maintain current state

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Fedders R407C service manual XI. Device Protection Measures, Heat mode protection applicable on Heat Pump Unit only

R407C specifications

Fedders R407C is a commonly used refrigerant that has made significant strides in the air conditioning and refrigeration industries. Developed as a replacement for R22, R407C blends three refrigerants: R32, R125, and R134a. This combination gives it versatile applications and makes it a popular choice in residential and commercial systems.

One of the main features of R407C is its zero ozone depletion potential (ODP). This is crucial in an era where environmental regulations are stricter and focus on reducing substances that could harm the ozone layer. R407C also boasts a relatively low global warming potential (GWP) compared to other refrigerants, which aligns with the growing demand for low-impact environmentally friendly solutions.

Technologically, R407C is compatible with many existing systems, particularly those designed for R22, making it a favored transitional refrigerant during the phase-out of ozone-depleting substances. However, it is vital to note that R407C operates at a higher pressure than R22, meaning that certain system components may need upgrading to ensure optimal performance and safety.

In terms of thermodynamic characteristics, R407C has a refrigerating effect similar to R22, making it efficient for cooling purposes across various applications. It has good heat transfer properties, which translates to efficient energy use in both residential and commercial installations. The refrigerant operates effectively across a broad temperature range, making it an ideal choice for air conditioners, heat pumps, and chillers.

Moreover, R407C is a near-azeotropic blend, which implies that it maintains its composition during evaporation and condensation. This characteristic helps in minimizing the risks of refrigerant fractionation, allowing for consistent performance over time.

Another noteworthy aspect of Fedders R407C is its favorable safety profile. It has a lower toxicity level compared to some other refrigerants, which enhances its suitability for varied applications. Additionally, it is non-flammable under normal conditions, making it a safe option for different installations.

In conclusion, Fedders R407C is characterized by its environmental safety, excellent thermodynamic qualities, and compatibility with existing refrigeration systems. As industries strive to meet new environmental regulations, R407C serves as a reliable option, providing performance without compromising on ecological concerns. Its pivotal role in transitioning to greener alternatives makes it a critical refrigerant in today’s climate-conscious market.