Hello , i am an refrigeration engineer and my air con in my vectra isnt cooling as well as it used to i think their might be a leak somewhere in the system and i need to top it up with some 134a...

their is not much of a tempreature difference on the suction and discharge pipes on the compressor i need to put my guages on to the system to check the pressures (static and back) but i have a problem and that is.. i dont have a valve which goes into the valve already on my car to convert to 1/4 inch to fit my guage hoose connection. it looks a bit like i will have to buy a adaptor to allow me to DIM ( do it myself ) but i was trying to find one on the internet but i cant seem to source it and i was wanting to know if anyone has one who will be willing to sell or know where to get them..

Thanks
mark mcc