AC system flush? Hose muffler? Oil? (Page 1/1) ninedriver JUL 19, 02:35 PM A few ac questions so I figured I’d lump them all together… I’m replacing the ac compressor and need to flush the system for the new one. I’ll also be replacing the orifice tube and accumulator. There is a hose set that attaches to the compressor and runs to an attachment point on the left side of the engine compartment. Is it ok to flush these lines? One of them has a “muffler” on it. Is that ok to flush? Should (can) it be replaced? The new compressor is a four seasons HR6 58255 that comes filled with 3 ounces of oil. Since I plan on replacing the accumulator and flushing the entire system I assume I’ll remove the rest of the oil. This is a 134a compressor but it doesn’t list what kind of oil it contains. So, how much and what type of additional oil should I add? (Mineral, ester, pag). (( If pag, which one…46, 100, etc?)) fierofool JUL 19, 07:18 PM Your compressor should have specified the oil in it's enclosed paperwork. The compressor gets 4 oz. oil after a flush so just add 1 oz. to what's in it and the accumulator gets 4 oz. of oil if a new installation. The muffler is just that. It absorbs and quiets the compressor pulses. It is of no concern when flushing. My Four Seasons HR6 58255 compressor came with Ester 100 oil already in it. I would recommend purchasing a R134a compressor cycle switch that screws into the accumulator rather than trying to adjust the R12 cycle switch. Four Seasons 38846, AC Delco 15-542, NAPA 207069, Santech MT2157 I would also suggest that you purchase a small bottle of Nylog Blue for lubing all your seals and O-rings. It is a lube and seal that doesn't dry out and is fully compatible with all refrigerants. Unless you are in the AC repair business, you will never use up the 2 oz. bottle. Less than $10 at most any AC supply warehouse. RWDPLZ JUL 19, 07:53 PM The muffler on the Fiero is fine to flush, it's empty, just give it time to drain and dry. https://www.fiero.nl/forum/...160323-2-129036.html Four Seasons usually has a good tech line, they should be able to tell you what oil is in it. https://www.4s.com/en/contact Fiero total oil capacity is 8oz. Should be Ester or PAG for R-134A, Mineral oil is R-12 only. Mineral oil is only used to lubricate the o-rings in an R-134A system. PAG should NOT be used to lubricate o-rings in an R-134A system, it can cause corrosion. I haven't tried Nylog Blue but I've heard good things... ninedriver JUL 19, 08:13 PM Thanks for the replies guys. Fierofool, I went ahead and ordered the clutch cycle switch and the nylog blue, good call. RWD, thanks for the advise and links. I loved the inside pic of the muffler. Not what I was expecting…. I looked everywhere in the compressor box and instructions and all I could find was “this compressor is pre charged with 3 ounces of oil” , nowhere does it indicate what kind. I’m going to reach out to four seasons as I don’t want to put the wrong or incompatible oil in the system. Thanks again. And with temps in the upper 90’s I’m looking forward to getting this done.