Save that email for future reference in case something goes south. They didn't advise adding any oil to the components? I guess they are expecting the freon to carry it along and deposit it where it will. Be sure to do as 79USA1 said and spin the compressor by hand to make sure it isn't going to hydrostaticly lock up. As for your question, no, you will not be evacuating anything. On a regular system that contains freon you are supposaed to evacuate the old freon into a reclamation machine. It is illegal to evacuate any kind of refrigerant into the atmosphere. If any oil gets out the machine will separate it. Sealers will damage the machine so if a shop suspects that they may refuse to evacuate your system. You normally install all the components adding the specified amount of oil to each. Then you make all the connections with new "O" rings and seals lubricating them with some oil. Once everything is in place and double checked, then you begin vacuuming the system down. First you try to get to 30" vacuum for 5 minutes, and then you shut the valve and watch the gauge. You need for the system to hold vacuum for at least 5 minutes. If it won't then you have a leak. I have seen systems hold vacuum for half an hour and still leak later on. Water boils at 29" vacuum so they specify 30" to be sure. So any water vaporises and gets carried out by the vacuum pump. They recommend doing a deep vacuum (30") for at least an hour. I sometimes go and have lunch or do something else for several hours and just let the pump run. Especially on a system that I did not replace the accumulator. After vacuuming then you are ready to add the freon. Did they advise how much to add? On most cars there is a spec, usually a sticker under the hood, but in the manual for sure. R134a requires a specific amount- no more- no less- for optimum performance. The old R12 way of adding more until it gets as cold as it can won't work with R134a. I use a digital scales to get the exact amount. I place my 30lb can of freon on the scales and slowly add while watching the digital readout. Then I check the low and high side gauges to see what they are doing. At this point you will know if the system is functioning properly or if there are any problems. If you can't get the specific amount of freon to add, then you will at least need the low and high side pressures @ what ambient temperatures recommended. Then you can slowly add freon while watching the gauges and stop when you are getting the right results. It only takes several ounces of freon to close the low pressure cut-off switch so don't be fooled- you must watch the gauges.
