OK PPL here I go if any body is interested you can make a compressor from junk that will give good( actually great) service ( you must have gages or at least 1 hose to connect to the system about $15.00 firstly the concept of using engine vacuum to evacuate an air conditioner system is ridiculous ... it aint going to work .. )in short what you are doing when a system is evacuated is 1 removing noncondensible gasses 2 boiling off water vapor 3 and checking for leaks to do this the right way you need 28 actually 29 or more inches of mercury I usually do this for at least 1 hour... unplug my compressor and check the gauges if the system holds vacuum ..add freon now here is what you need
an old refrigerator motor( this is a compressor its usually big black and makes the characteristic humming sound we are all familiar with) however a air conditioner dehumidifier or water cooler will do the same.... any thing that has a compressor in it will work 1 remove the compressor its usually bolted in there will be 2 lines commeing out of the compressor one is a high side the other is a low side now cut the lines useing a tubing cutter so you will have a clean cut you want maybe 3 or 4 inches of line on the compressor if you have used a air conditioner there usually wires going to a capacitor this looks like a oval metal can with wires going to it leave the wires connected and where the wires come out of the unit use the appliances electrical cord and plug reconnecting them using wire nuts and electrical tape so far you have spent nothing!!!! well sorry I forgot the tubing cutter available at home depot a small one should be under 10.00 now go to any air conditioner supply house _http://corporate.johnstonesupply.com/_ (http://corporate.johnstonesupply.com/) take the compressor with you ,and get a solder tee ( these range in price se ...$5.84 to $16.29... )that will fit those nice clean cut tubes on the unit .... and solder the tee on the suction side only!!! use one do not close ,crimp or shut off the pressure side ... now you have a vacuum pump that will work just fine and it cost nothing PS a plastic milk crate works just fine to carry this in ... go get em mike collins phila 1985 500 sec