Hombre S Regular Cab 4WD V6-4.3L (1999)
Expansion Block/Orifice Tube: Description and Operation
Expansion (Orifice) Tube Description
The plastic expansion tube contains a fixed diameter tube.The tube has a mesh filter screen at either end. The expansion tube is located in the evaporator
inlet pipe. The expansion tube creates a restriction to the high-pressure liquid refrigerant in the liquid line. The flow of the refrigerant is then metered to
the evaporator as a low-pressure liquid. When the engine is turned OFF while the air conditioning is operating, the refrigerant in the system continues to
flow. The refrigerant flows from the high-pressure side of the expansion tube (orifice) to the low pressure side until the pressure is equalized. The
equalization may be detected as a faint sound of liquid flowing (hissing) for 30 - 60 seconds. This is a normal condition.
You may not need to replace the expansion tube when the system diagnostics indicate a restricted expansion tube. Remove the following materials found
on the screen with compressed air:
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Metal chips
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Metal flakes
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Metal slivers
You may reuse the expansion tube under the following conditions:
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The plastic frame is not broken.
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The expansion tube is not damaged or plugged.
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The screen material is not worn.
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The screen is not plugged with fine gritty material.
