Your discription better describe's welding equipmet than hvac. There is a sticker or metal tag attached to the condenser houseing listing voltage,amperage,refrigerant,make and model,post a picture of that tag to make it easier for us to help you. What technical info are you seeking? Are you planning to repair it yourself? Based on your questions,it sound's like you just need to have another tech look at the unit.

You are right. The thing is that I´m far away from my country side home (another city) and I want to be sure of what the technitians are telling me. So any information about where to look for that Miller model will do. Thanks for your attention.

edgar,few here are willing to help you research obsure,discountinued pieces of equipmet not knowing exactly what information you are looking for and what it will be used for when and if any is found. I fail to understand how it would help you "be sure of what the technicians are telling me" if you had schematics for the unit. Most of us find everything needed on the scematic glued to inside of access panel.