I forgot to mention. I aquired a real strong vacuum pump from the ebay listings on vacuum pumps. Usually you have to fit a fitting to modify the connection on them to work with ac hoses. That is minor as the real pumps are designed for continious service in comparison to the average cheaper hvac pump.

Most decent pumps will be two stage as well. The smaller pumps in the real vacuum pump world seem to come up as pretty much surplus from time to time. All I am certain is at the present time you can still get a better cheapie type vacuum pump from ebay for less money. I looked. Same with new gauge sets.

Actually there is a cheap new viot but looks like a two stage on ebay with less than two hours to go. Two stage is not the cheapest model either. Brand new with no bids and starting is .99. At this time it is one in the afternoon here in eastern Canada. May or may not attract any bids and it is listed under vacuum pump on ebay. . Someone should grab it if the original poster does not. Possibly comes out of the same Chinese factory the harbour freight one does. I think it is a better model than their 99.95 edition though.