Using shop compressor as a/c vacuum pump?

scottb · 05-29-2006, 10:19 AM

I thought I read somewhere that I can use my little garage compressor as a vacuum pump when doing a/c work. Is it as simple as connecting a nipple to the air input side of the compressor with an adapter to fit my a/c manifold, and then connecting it to the low side of my a/c system?

If this is "do-able," it seems to me that a 3hp compressor will do at least as good a job as the smaller specialized vacuum pumps, but I'm interested to hear from some of the a/c gurus on the board. (Jim Sims, are you out there?)

Rick V · 05-29-2006, 10:57 AM

I have a vac pump that runs off of a compressor. It is the only way I now about doing it the way you are refering to. These pumps are fairly cheep and small. Might just be worth your time to buy one instead of rigging something. You don't need gauges to use this pump but doing ac work without them is not cool. (pun intended)

scottb · 05-29-2006, 11:03 AM

Thanks, Jim!

Motorhead-45 · 05-29-2006, 11:05 AM

Autozone offers a vacuum pump under their loaner tool program! The price is right!....FREE!

Motorhead-45 · 05-29-2006, 11:16 AM

Quote:

Originally posted by Jim Sims
"Autozone offers a vacuum pump under their loaner tool program! The price is right!....FREE!"

If you use one of these loaners also buy a quart of vacuum pump oil and change it before using the pump; the oil becomes water laden and prevents the pump from achieving good vacuum levels.

And the irony of it all is that Autozone doesn't stock vacuum pump oil. I had to source mine from elsewhere the first time I borrowed the Autozone pump.

Tex3 · 05-29-2006, 11:26 AM

Quote:

Originally posted by Jim Sims
The venturi type vacuum pumps (they use a flow of compressed air by a hole or venturi) do not reach a low enough vacuum for a long enough time for A/C servicing purposes.

yeap like the one in the link only $16.99
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92475

Rick V · 05-29-2006, 12:36 PM

Quote:

Originally posted by Jim Sims
The venturi type vacuum pumps (they use a flow of compressed air by a hole or venturi) do not reach a low enough vacuum for a long enough time for A/C servicing purposes.

I would beg to differ, mine pulls 30 inches and holds it as well as the old school robinaire eletric. The trick is to have enough air pressure to use it. I bought mine from Matco tools a few years back and it has yet to fail in it's performance.
It would be nice if it wasn't so dang loud.

Rick V · 05-29-2006, 02:57 PM

Quote:

Originally posted by Jim Sims
can your compressor/tank supply air for three hours at the venturi pump's rated pressure and consumption?

Yup!,
I might also add I only use my vac pump at home. When at work I use the big'ol 4 wheeled unit...............................I quess that should tell me something.
I guess back to the origional question, no you can't use a compressor as a vac unit. Sorry for the thread jack.

Zeke · 05-29-2006, 03:10 PM

Quote:

Originally posted by Rick V

I guess back to the origional question, no you can't use a compressor as a vac unit.

Might also pull the oil up in the compressor and make a mess in the tank. The point about it feeding into the A/C system is good. I don't know, but it might do that too. You'd have to see what happens when they equalize at whatever vacuum the compressor would pull.

Venturi vacuum? I'd love to see one. Lordy, I'd think you'd need a rotary compressor and some serious volume to accomplish such a feat. Goes to show you what I know about engineering.