I am replacing all the parts except for the evaporator core and the hoses attached to the expansion valve. My question concerns the two spring parts located on one of the hoses and the drier. Some forums suggest these parts are unnecessary, while others say they are essential. Are these parts needed, or are they obsolete for the R12 system?
Additionally, I have a gray plastic hose coming out above the expansion valve that is capped on my truck (highlighted yellow). What is this hose for, and do I need it for the AC to function properly?