Automotive Air Conditioning Information Forum

Check all of your service hose connections. A tiny leak in any of the 4 temporary connections or a handwheel valve stem can be enough.

If you suspect a connection, disconnect the high side at the vehicle, pull again & see if the vacuum holds. Try the same test in reverse. If you get the same leak rate it is the system not the test equipment.

Sometimes you get some shaft seal leakage under vacuum as well. I use a micron gauge and if it holds below 1000 for half an hour I will charge it.

Everything leaks, 1 molecule per month or 1 pound in two years - which one would you be satisfied with?

From your description I would pull a third time & charge it, were it my own car.

Wow sound advice..thanks for that. Running out of time tonight in the good old U and K.
May have to try this tomorrow.. My choice would be no molecules lost ever but its not a perfect world! Also I maybe overthinking this one. Never thought about the shaft seal possibly leaking under vacuum and my crap gauges!
Can you explain pulling to 1000 micron..does that equate to inches of mercury maybe 30?

Microns allow you to spread the scale somewhat...

https://www.engineeringtoolbox.com/vacu ... d_460.html

Anyplace between 400 & 1000 microns is great for automotive work. For rigid plumbed stationary systems you can go lower.

That's a hell of a lot of suck!

Anyway success !..the vacuum is not a good idea for checking for leaks as I have now seen but nitrogen is..My trusty aircon guy came round with his bottle of gas and we pumped it up and watched it of coupla hours and all good. In fact as the morning warmed up the pressure went up slightly.
Now all I gotta do is put the all the car back together around the aircon if I can remember where it all goes!

Fixed it Bohica ! PM sent to you..please read.