I would change the cabin filter anyway, once you see mold growing on them, you are more inclined to change them often.
You need to put some gauges on the system. If the compressor is engaging, Pressures are good for R12&R134, the low side (on a good working system), should be around 30-35 PSI around 2,000 RPM. For BAR pressure it converts to 2.0-2.4, and millibar scale is 2070-2400. Thats the Low side. The high side will differ with R12 and 134. 134 pressures are higher on the high side. Thats why you never convert a 12 system to 134. Anyway, the pressures should be on a 12 system around 220-250 PSI, BAR- 15-17.2, and millibar would be 15170-17235. The aux fan should be coming on at the latest 250 PSI. The 134 system like I said runs at higher temps. Right around 250-275 PSI. The aux fan should be coming on around 270-275 PSI. Hope that helps, the only way to diagnose an a/c system is to put gauges on it and read the pressures. Let me know what they are and I will tell you what is wrong. By the way, the system in that car will only let the cabin air being cooled to go to 41 on the F scale. And they are notorious to have a bad high aux fan relay go bad. It is located under the bolted cover of the fuse box, it is green with a 30 amp fuse.
How is Okinawa doing? I miss that place. My wife's Brother and Mother live in Japan, everytime we go we hop on the bullet train and check out the beautiful art. Man I miss Japan!