a simple one

[npp230v]

went to service some split wall mount units service went well they were cheapy b&q ones with no valves
or test points any where service went well apart from1 had a test point on the entrance to the outside unit it was a standard 407a the valve had an allen key at the side to front seat etc but no matter what i did the test point still had pressure the is this normal

[icecube51]

first of all..407a ??? if the unit had refrig ,it always gone have presure. did you check youre gauges ?? is the pin not to far inwards ?? is it pussing the shraeder open ??
Ice

[npp230v]

gauges are fine hoses fine it was every time i tried to screw the hose on i had vapour escaping is this usual or can you isolate like a normal service valve

[nike123]

gauges are fine hoses fine it was every time i tried to screw the hose on i had vapour escaping is this usual or can you isolate like a normal service valve

That is normal!
You could isolate it with quick coupler fitings!

[Brian_UK]

Gee, you frighten me, have you not connected guages to a system before ?

[npp230v]

yes several times but never had vapour pissing out before as i saked is this normal

[nike123]

Ignore, bad joke!

[Peter_1]

Please, insert end points in your lines and capital letters at the beginning of a new one because I barely can read you message.
Like you describe, they're all made this way, so there's nothing special about it.

[icecube51]

maybe look if the pin on your gauges is not to far out,the one that pusses the shreader in, so when you loosen up there comes to much vapor out the connection.

Ice

[npp230v]

ok thaks guys

[icemakerman]

from what u describe it sounds like the schreader valve on the condensing unit is leaking. if both lines have allen key shut-offs the system could be pumped down to allow replacement of the schreader valve. After replacement the charge should be checked