Friedrich 2003 service manual Check Valve Operation, Heat Pumps Reversing Valve See Figure

CHECK VALVE (See Figure 39)

A unique two-way check valve is used on the reverse cycle heat pumps. It is pressure operated and used to direct the flow of refrigerant through a single filter drier and to the proper capillary tube during either the heating or cooling cycle

Figure 39

One-way Check Valve

(Heat Pump Models)

Figure 40

(TO INDOOR COIL) (TO OUTDOOR COIL)

NOTE: The slide (check) inside the valve is made of teflon. Should it become necessary to replace the check valve, place a wet cloth around the valve to prevent overheating during the brazing operation.

CHECK VALVE OPERATION

In the cooling mode of operation, high pressure liquid enters the check valve forcing the slide to close the opposite port (liquid line) to the indoor coil. Refer to refrigerant flow chart. This directs the refrigerant through the filter drier and cooling capillary tube to the indoor coil.

In the heating mode of operation, high pressure refrigerant enters the check valve from the opposite direction, closing the port (liquid line) to the outdoor coil. The flow path of the refrigerant is then through the filter drier and heating capillary to the outdoor coil.

Failure of the slide in the check valve to seat properly in either mode of operation will cause flooding of the cooling coil. This is due to the refrigerant bypassing the heating or cooling capillary tube and entering the liquid line.

COOLING MODE (See Figure 40)

In the cooling mode of operation, liquid refrigerant from con- denser (liquid line) enters the cooling check valve forcing the heating check valve shut. The liquid refrigerant is directed into the liquid dryer after which the refrigerant is metered through cooling capillary tubes to evaporator. (Note: liquid refrigerant will also be directed through the heating capillary tubes in a continuous loop during the cooling mode).

HEATING MODE (see Figure 41)

In the heating mode of operation, liquid refrigerant from the indoor coil enters the heating check valve forcing the cooling check valve shut. The liquid refrigerant is directed into the liquid dryer after which the refrigerant is metered through the heating capillary tubes to outdoor coils. (Note: liquid refriger- ant will also be directed through the cooling capillary tubes in a continuous loop during the heating mode).

Figure 41

(TO INDOOR COIL) (TO OUTDOOR COIL)

HEAT PUMPS: REVERSING VALVE (See Figure 42)

A reversing valve is used to change the refrigerant flow within the system to permit heating or cooling.

The reversing valve consists of a main valve body which houses the slide and piston, plus a pilot valve which is activated by a solenoid.

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