many thanks for that quick reply sir jick...
unfortunately, you just confirmed that my NBR-70 o-ring service kit has no use at all....
i have been trying to look for HNBR here (your out of the country right now I presume) but to no avail. most a/c suppliers simply say that nbr will do and that Hnbr is quite costly for a yearly a/c maintenance.
From your end, may i know if their representation is correct or acceptable, that is to use nbr instead of hnbr taking into consideration your earlier post? again,many thanks... regards