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  1. #1
    Join Date
    Aug 2017
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    I cant find any information on these old shaft drive vacuum pumps?

    Hello, I am looking for a vacuum pump in order to draw a vacuum on vehicle a/c systems. I do not do this for a living i just prefer to do all my own work. So instead of taking the easy way out and buying a harbor freight vacuum pump i decided i want something american made. I was searching ebay for some old usa made pumps and have come across a few like a (marvac act-71). I cant post pictures yet because this is my first post.

    I want to know where i can find information on them such as micron rating and if anyone has experience with using these to draw a vacuum. Will these draw a deep enough vacuum for automotive a/c work? I know you can get these in single stage and double stage. I would get a double stage version. Also i was reading about cfm rating and it does not seem to be a big deal to get a small cfm rating pump for automotive a/c work. I see alot of these pumps are 1.6 cfm and very few are 3 cfm. One i found is 6.2 cfm. Should i get the 6.2cfm one or would a 1.6cfm one be good? What benefit would i have to get the larger cfm over the smaller one or vice versa? Im mostly concerned with knowing whether these will draw a deep enough vacuum. I know it all depends on the condition of the pump but lets just pretend that the pumps are all in perfect working order. Thanks

  2. #2
    Join Date
    Nov 2008
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    I always used to use those venturi vacuum pumps that you can pick up at harbor freight for under $15 with their 20% coupon. You can also build one yourself and call it american made. I've seen people pull a vacuum on their vehicle a/c using the vacuum from the intake manifold. I've also seen people open the high side and use the car's compressor to pull a vacuum.

    I've never had any issues with the A/C in any of the vehicles I've used the venturi pump on. I located and fixed the leaks first of course.

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