Trying to charge my A/C from the low side using manifold gage system. The thread size does not seem to be a standard size. The 1/4 NPSI female fitting does not match up to the connector hose. I bought a coversion kit to R134 but the disconnect that fits my hose unit is not the proper thread size to screw on the fill fitting. The whole problem is the size of the female threads on the fill location. Does anybody know of a fitting that will adapt to the common size. Tried taking it to a tech but they wont touch it because of the R12
