On my 1998 Frontier I had to replace the high pressure AC line in 2017 due to a pinhole leak on a 119F day. I cannot remember if the new/only available high pressure line came with O-rings, but the fitting depth on the compressor end was way different, I had to cut the new line's fitting shorter (but at least the groove was in the correct location).

Now I wonder if I used a 2.0mm width O-ring where I should've had a special 2.43mm width O-ring. Because UV light shows refrigerant leakage at both ends, factory compressor, 290K miles.

In 2018, the AC compressor seized up on my 2004 Frontier seized and I replaced the compressor, condenser, drier, and backflushed lines with solvent. UV light shows leakage at both lines at the compressor, but slower leakage than on the 1998. I cannot remember if those parts came with O-rings or not (cost-savings, you know !!!).

The Frontier service manuals list specifications of these O-rings at 2.43mm width, wonder if I used 2.0mm O-rings and didn't realize it.
For whatever it's worth, looking up the Nissan part numbers provided in the service manual on the Nissan sites shows that it won't fit, and "search for parts that fit" comes up with the #8 O-ring...so weird, and Nissan is always replacing part numbers with new ones.

I want to have new/correct O-rings on site before I start taking apart, really don't want to replace the drier too so no good to then order.

I'll try to check the sizes I have in that Santech MT2571 kit and other HNBR O-ring kits I have already, not super sure I can read difference between a 2.00mm O-ring and a 2.43mm one.

I went online, and if I have to order correct Nissan-size O-rings, will cost me about $50 shipped for three of #92472-N823A and one of #92474-N823A. Almost $9 each plus about $15 shipping !!!

I haven't yet called local Nissan dealers' parts department, but expect each will be about $12 (MSRP) but no shipping, so would be about $48 not much difference, and I'd have to drive to the dealer !!!!

Why can't manufacturers use commonly-available hardware like O-rings???? I know: $$$$