Access ports will need to be brazed in or there are piercing valves that can be installed. Depending on the vintage of the unit. It may have been charged with R-12. Hopefully, there is a data plate that mentions the refrigerant and charge weight. The A/C tech won't have the gas on his truck. R-12 isn't produced any more. Maybe, he will have a drop in gas. In your endeavors to patch the hole. If you got flux inside of the line. The flux will contaminate the oil, reducing the dielectric strength of the oil. Over time, the integrity of the insulation on the motor windings will be breached. However, the tech can install a couple of Sporlan HH driers. The driers will clean the oil. They cost about 50-75 bucks each. The time it takes the tech to chop in access ports, braze the leak, run the unit in a vacuum and recharge the system. You can buy a brand new cooler. Unless, the tech will make a deal. You're over your head with this.