Well in time of one month got my ac serviced thrice.
Car is 92 accord with original everything . Each time we serviced it we build pressure and vacuum and the readings do not indicate any leak. Also rotated compressor clutch to see if it causes leak bit no.

Leak only happens when car is left under Sun fit half a day which means car is under constant 47 degrees Celsius or more.

I can't figure out leak source. Only I think during pressure and vac test gauge was hooked on and without it there is leak. Can those high and low side ports leak? If yes what is the solution? Can compressor safety valve be culprit?

 

Did you ever add dye?

 

The service ports are soo common to leak and won't show up when the gauges are connected. Spray some soapy water on them and see.

 

No uv dye not available here .

 

ok I'll do it. Do you think they have relation with outside temp. Higher the temp greater the leak

 

refrigerant is green and I have had leaks previously at the charging port...it's not especially easy to see but it is visible as light bubbles

 

They also sell refrigerant detection devices. The ones at harbor freight are cheap, but I heard theyre still pretty good. Assuming the system has a charge, make sure the engine is off...and slowly trace the lines. Common places are the valves, and then the lines/fittings coming in/out of the condenser(Where it is really hot, and under high pressure)