Top Up dash A/C

[birdshill123]

Our 88 FC still has an R12 system. The previous owner had BB replace
the compressor about 3 or 4 years ago. It has always worked really
well. We are in Mexico and I guess it lost some Freon while in storage.
Still cools but not as cold as normal. I can buy a can of R12 at any
auto parts store. I have recharged my last MH that had R134 but it was
a conventional system. Where do I find the low pressure fitting to add
Freon. I see a capped fitting under the doghouse right next to the
compressor and it has a hose attached with a hose clamp. I assume that
is the low side. Or are there fittings up on the roof?? Any help
appreciated and please no environmental lectures.

Thanks

Bruce
1988FC35