well i take it you don't know so first must make sure this the problem, and if so you need legally if system is empty you use a tool called a Garter Spring tool that how you remove if its a UN threaded at one end only, if the system has gas in it you need to know how to properly evacuated the system and do the recovery of the freon,. i assume its R-134-A Freon, then do your repair then you need to put the system under vacuum and , before you recharge it then you must add the correct amount of refrigeration oil , and the correct kind, then proceed to charge and if you do not own a A/C warmer charging machine then you will do it the old faction way with the Gage's, and know what your doing ,the hose with garter springs will have two refrigeration O - rings that you are suppose to replace when you do a hose removal, and oil the O-rings must be pre oiled in refrigeration oil before you install it, OK got it good Hope this helps you, but the tool your inquiring about is a Called Garter Spring Removal tool and there are 5 sizes, and they go by color