OPERATION
The orifice tube provides a restriction to the high-pressure liquid
refrigerant in the liquid line, metering the flow of refrigerant to the evaporator as a low-pressure liquid. The expansion tube and orifice are protected from contamination by filter screens on both inlet and outlet sides. The tube is serviced only as a replacement assembly.
When the engine is turned "OFF" with the air conditioning operating, the
refrigerant in the system will flow from the high-pressure side of the expansion tube (orifice) to the low-pressure side until the pressure is equalized. This may be detected as a faint sound of liquid flowing (hissing) for 30 to 60 seconds and is a normal condition.
When system diagnostics indicate a restricted expansion tube, it may not be necessary to replace it. Metal chips, flakes, or slivers found on the screen may be removed with compressed air. The expansion tube may be reused if:
- The plastic frame is not broken.
- The expansion tube is not damaged or plugged.
- The screen material is not torn.
- The screen is not plugged with fine gritty material.
---------- Post added at 01:43 PM ---------- Previous post was at 01:42 PM ----------
OPERATION
The sealed accumulator assembly connects to the evaporator outlet pipe. It functions as a liquid/vapor separator that receives
refrigerant vapor, some liquid refrigerant and
refrigerant oil from the evaporator. It only allows refrigerant vapor and oil to flow to the compressor.
At the bottom of the accumulator is desiccant that acts as a drying agent for moisture that may have entered the system. An oil bleed hole is also located near the bottom of the accumulator outlet pipe to provide an oil return path to the compressor.
A low-side pressure service fitting is located on the accumulator. A similar service fitting is provided for mounting the cycling pressure switch. It is not necessary to discharge the system to replace the switch. The accumulator is serviced only as a replacement assembly.
---------- Post added at 01:46 PM ---------- Previous post was at 01:43 PM ----------
You replace the orifice because overtime it can get a little cloggy reduceing efficiency and puts more stress on the compressor. The accumulator has a drier in it that eats up moisture. It is standard practice to replace it if you have to open your system so that the desiccant has the capacity to remove any moisture introduced into the system when servicing.