Vacuum pumps?

[Jason280]

I've always wanted to learn A/C work, and have been trying to find a deal on a decent vacuum pump. Local pawn shop has a single stage OTC that I can probably get for around $40, except I know nothing about them. Should I hold out for two stage, or will the single be enough? I *believe* its a 2 cfm, but not sure.

Any suggestions?

 

[Climatecreator]

It depends what you're doing with it.

First off we use multi stage for deeper and faster vacuum.

You can test the pump with a micron gauge, get one of those first.

If you're just putzing around then time isn't an issue, you can just let the pump run as long as it takes to get to the vacuum level you need.

Back in the day we ran em for 45 min to hours depending on system size and our best guess on humidity level during installation.

My how far we've come....

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[Ohmthis]

Is this for automotive or residential AC? That would work fine if for automotive. For residential, it will be slow to pull most systems down. Always make sure to use fresh oil in them and to test it, you really should try it on a tank to see how long it takes to pump down. I have a 3 cfm for automotive and a 7 cfm 2 stage for residential systems. The little one would do a resi system, but I need to think about time $$$$.

 

[Jason280]

Strictly automotive.

 

[Ohmthis]

That one would work fine, check it out with a set of gauges at least. Btw, love your avatar��

 

[6PTsocket]

While we are on the subject, how well do those vacuum from air pressure devices work? I know how they work but do they work well enough to be useful?


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[theoldwizard1]

While we are on the subject, how well do those vacuum from air pressure devices work? I know how they work but do they work well enough to be useful?

From what I have heard, NO !!

 

[zeke markham]

While we are on the subject, how well do those vacuum from air pressure devices work? I know how they work but do they work well enough to be useful?


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Those are mostly for laminate and composite work, they won't pull enough vacuum for A/C work.

 

[Davefr]

I've always wanted to learn A/C work, and have been trying to find a deal on a decent vacuum pump. Local pawn shop has a single stage OTC that I can probably get for around $40, except I know nothing about them. Should I hold out for two stage, or will the single be enough? I *believe* its a 2 cfm, but not sure.

Any suggestions?

To pull <<500 microns you need 2 stage and low leak fittings/hoses.

Bigger is not better when it comes to CFM. 2 CFM is probably OK but 1 CFM would be better.

 

[6PTsocket]

Those are mostly for laminate and composite work, they won't pull enough vacuum for A/C work.

I'll take your word for it but the place I see them advertised is HF with auto AC fittings for 12 or 134a. It wouldn't be the first time they sold something that does not work well.

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[AA/FC]

I'll take your word for it but the place I see them advertised is HF with auto AC fittings for 12 or 134a. It wouldn't be the first time they sold something that does not work well.

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I had one of those cheap air powered vac pumps that I tested with my digital micron gauge connected directly to the pump..... I forget the exact number but it was NOT good enough for doing A/C work.

Edit: I just looked at an old post I made about vacuum pumps on another forum about 11 years ago...... when I tested the air powered pump with my digital micron gauge, the lowest I could get was 6500 microns. Some guys will argue the micron level required to properly charge an A/C systen... some say 500, some say 1000. I'm not going to argue here with anyone, but 6500 is nowhere near good enough!

.

 

[royesses]

Read this link about air powered vacuum pumps:
http://aircondition.com/tech/questions/38/Air-Powered-A{47}C-Vacuum-Pumps

The 2CFM single stage should work great for automotive use. You should take the system down to 500 microns and most single stage pumps I've tested will go down to 300 microns.
According to the oil companies too low a vacuum can cause a breakdown of some refrigeration oils. I've not seen that happen but I do take their word for it. A micron gauge is the one tool every one working on refrigeration systems should have besides a manifold gauge set and vacuum pump.

Roy

 

[Jason280]

I looked at the pump again today, its actually an ATD single stage 1.5 cfm pump...