Tim wrote: Sat Sep 13, 2025 9:37 am
I don't know the size of the o-ring off-hand. I always just matched them up in my Master kit. Autozine and Napa are suppliers of Santech, which is one of the big companies where I still do catalog stuff. The issue is that you can't go by my year, make, or model. Kind of have to match it up. The Santech kit for this vehicle is an MT2571. Might look if it has a better-fitting o-ring.
Maybe:
MT0236-4
MT0244-10
This morning I tried to look up on official Nissan parts sites for the 1998 Frontier O-ring, and it doesn't appear when searching for a 1998. When I search for my 2004 Frontier, one does show. These two Frontiers use the same AC compressor 14-3138NEW/DKV14C1GR, but have different discharge lines. The 1998 is leaking from O-rings at both ends, was replaced in 2017 due to a pinhole;
ackits.com shows discharge line 57-0135 with O-rings on it, is that true?
2004 is leaking from both ports on the compressor but not at the discharge line to condenser connector; I replaced its condenser, compressor, drier and backflushed with solvent in 2018 due to compressor seizure.
I have Santech MT2571, used O-rings from that. I also have another AC O-ring "kit" for Nissan, and an assortment of green refrigeration O-rings from Harbor Freight.
Even though the 2004 does have leakage, the rate of leak is significantly slower than on the 1998, so maybe the 2004 should be treated as "touch up" with 6 oz. R134a where the 1998 should get new O-rings.
Photos of the 1998 leaks
