Refrigerator Troubleshooting Diagram

Archive for the ‘Condensing Unit’ Category

Refrigerator Solenoid Valves

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The solenoid valve is an electrically-operated valve. It uses an electromagnetic field to raise a pilot valve. The gas pressure raises the main valve allowing flow. The flow will continue as long as the pilot valve is held off its seat. The valve in Fig. 12-8 is typical. It can be used with liquid as well as vapor or high-pressure gases. In the condensing unit, it can be used for a pump-down liquid-line valve or an anti-slug valve. If used for a pump-down valve, the unit must have a low-pressure control to stop the compressor operation. For use as an anti-slug valve, the valve is wired to close as soon as the compressor stops. It prevents any liquid in a vertical liquid line from dropping down into the compressor. When mounting a solenoid valve, it is good practice to orient the valve for operation in a vertical plane. This would require the inlet and outlet of the valve be in a horizontal plane. The electromagnetic coils are available in 24, 120, and 240 volts.

solenoid-valve

Written by sam

October 6th, 2011 at 3:49 pm

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Refrigerator Driers Dehydrators Diagram

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Driers should be used on both the liquid line and the suction line. The driers are designed differently and should be used for the purpose designated. The liquid line drier filters as well as dries the refrigerant as it leaves the condensing unit. The drier contains a desiccant and a strainer or sieve. The refrigerant flowing through the drier gives up any moisture it may be carrying to the desiccant. Any particles of a solid will be trapped and held in the drier. Most of these units are designed with a two-pound pressure drop across it. When a drier starts to become clogged, the pressure drop increases as a first indicator. Frost might form on the drier when it becomes clogged. The primary purpose of the liquid line driers is the protection of the metering device against dirt and moisture. No more than one liquid line drier should be installed in the liquid line at one time. If two or more are placed in series, the pressure drop could be severe enough to impede refrigerant flow. It is recommended that driers be installed on a vertical plane. The reason is that if the refrigerant charge becomes low, it would only flow over a small amount of the desiccant if the drier were mounted in the horizontal plane. In Fig. 12-4 a drier is shown. Notice the directional arrow that designates the direction it should be installed in the liq­uid line. If the drier is a bi-flow type, the directional mounting is not important because it will function in both directions. This type of bi-directional flow drier was designed for the use with heat pumps due to the reverse flow of the liquid when in cooling or heating mode. The suction line driers are bigger and usually have a Schraeder-type valve on the inlet side of the drier. By taking the pressure at the suction of the compressor and at the inlet of the drier, the pressure drop is easily found. The basic construction of this filter drier is the same as the liquid line. These filters are used to protect the compressor from contamination by acid, metal filings, etc.

drier-filter

Written by sam

October 5th, 2011 at 3:41 pm

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Refrigerator Hot Gas Mufflers Diagram

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Pulsations created by the pistons of a reciprocating compressor can create objectionable noises. When noise level is an important consideration, or hot gas lines are long, mufflers can be used to min­imize the transmission of “hot gas pulsations.” Figure 12-3 is an illustration of a hot gas muffler. This component is installed on the discharge line as close to the compressor as possible.

hot-gas-muffler

Written by sam

October 5th, 2011 at 2:41 pm

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Refrigerator Crankcase Heater

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The crankcase heater is a resistive heater that either mounts around the bottom of the body, or is an insertion type that slips into a well in the body, or a bar type that fastens to the bottom of the crankcase. It is the function of this component to energize on the compressor off cycle and transmit heat into the crankcase. The reason for this is to boil any liquid refrigerant that may migrate into the compressor. If an evaporator coil is higher than the compressor at the end of a cycle and the compressor stops, liquid might drop causing it to collect on pistons or in the crankcase of the compressor. On some cool days, refrigerant can condense in the compressor if it isn’t being used. The crankcase heater prevents a compressor from trying to compress liquid refrigerant, thus resulting in mechanical failure. The heater is usually wired through a relay that opens the circuit when the compressor is in operation. Some manufacturers leave the crankcase heater energized all the time by wiring it to the line side of the compressor contactor. This can cause a compressor to become too hot when operating, thus opening the overload relay and stopping the compressor operation.

Written by sam

December 23rd, 2010 at 2:31 pm

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Refrigerator Accumulator Diagram

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The accumulator is a very important component in heat pumps and low temperature refrigeration equipment. It is a vessel that collects any liquid refrigerant that is not boiled off in the evaporator. This prevents the compressor from slugging, (trying to compress a liquid) and causing major damage. In some extreme cases, a pipe-heater tape is wrapped around the accumulator and insulated. This ensures the refrigerant will boil sufficiently and enter the compressor as a vapor. Figure 12-2 is a typical accumulator showing how it works. This component is mounted in the suction line just before the compressor.

accumulator

Written by sam

October 5th, 2010 at 2:37 pm

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Refrigerator Receiver Diagram

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This refrigerant reservoir called the receiver is found in units that are using a TEX (temperature expansion) valve. When the heat load demand diminishes, the valve throttles the refrigerant flow. The excess refrigerant is stored in the receiver until a load demand is made. In some newer units engineers have designed some of the condenser coils slightly larger than needed to act as a storage area for excess refrigerant. In most light commercial refrigeration systems, along with heat pumps, the receiver is commonly seen. Figure 12-1 shows a typical receiver. This component is installed in the liquid line close to the condenser coil.

vertical-receiver

Written by sam

October 5th, 2010 at 2:35 pm

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