NA Miata a/c system

I decided to tackle my a/c not working. Injected some dye into the system, found a large leak at the fitting on top of the compressor. New o-ring solved that. Vacuumed down the system but it's only getting down to -10, which suggests there's another leak somewhere.

I followed the rest of the hardlines around as well as I could and didn't see any evidence of leaks, are there any other common areas I'm missing on a '95 miata?

I don't know about common, but the newest NA is now 27 years old...  I'd throw all o-rings, a drier, oriface tube, and condenser at least at it..

Behind the compressor pulley? 

Good luck finding a dryer. I think I found the last one on Rock Auto. Mazda does not carry them.

In reply to NOHOME :

In reply to wae :

Good to know.  I am still trying to figure out the hose build for the hybrid  Miata AC/with a Mustang  so mine sits on the shelf and I might need another if the first try does not work.

WonkoTheSane said:

I don't know about common, but the newest NA is now 27 years old...  I'd throw all o-rings, a drier, oriface tube, and condenser at least at it..

I'd find the leak and fix just the leak...  because all of those fittings are threaded aluminum and they will gall and destroy components when they don't come apart, or come apart in a manner that prevents them from going back together.

Old A/C systems is definitely a place where if it ain't broke, wrenches only make it worse.

spandak said:

Behind the compressor pulley? 

Reviving this thread because spandak was right, found the leak behind the pulley.

Then things got weird. Rented a/c gauges and a vacuum pump again, only to find it wouldn't draw any vacuum at all. Triple checked everything, gauges wouldn't budge from 0. Wrote it off to the vacuum pump being burned out, it had obviously been used, oil level was very low, suction was fairly weak.

Then I decided to throw a can of 134A at it just to see what would happen. Brand new can, a/c cranked full blast and...the simple gauge on the dispenser also won't budge off 0. Doesn't seem like anything is coming out of the can. 

Now I'm thinking the low side valve might be stuck? It would explain the consistently odd behaviour. Any other ideas?

If the system is discharged I would certainly suggest changing both the schrader valves either way.  They are cheap, easy to replace, and a likely place to leak.