compressed air driven vacuum pumps

[TrexMex]

Has anyone tried these?

http://www.wholesalepartsandtools.com/products/FJC_6900_Air_Vacuum_Pump-383-89.html

Do they work well? Do they break often? do I need to provide external Lubrication? (pneumatic inline filter/lubrication)

Any thoughts are welcome

 

[4x4junkie]

No, there are no moving parts in those pumps, no maintenance required whatsoever. They use a venturi chamber to produce a vacuum.

My experience is they don't pull all that great of a vacuum unless your compressor can sustain a continuous 6-7 CFM or more @ 110-120 PSI (most home compressors cannot do this, even my oil-lubed twin-cylinder Craftsman couldn't quite do it).

If you got a good beefy shop compressor though then it should work decent.

BTW, Harbor Freight Tools sells that EXACT same pump for $12.95.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96677

 

[kunar]

No, there are no moving parts in those pumps, no maintenance required whatsoever. They use a venturi chamber to produce a vacuum.

My experience is they don't pull all that great of a vacuum unless your compressor can sustain a continuous 6-7 CFM or more @ 110-120 PSI (most home compressors cannot do this, even my oil-lubed twin-cylinder Craftsman couldn't quite do it).

If you got a good beefy shop compressor though then it should work decent.

BTW, Harbor Freight Tools sells that EXACT same pump for $12.95.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96677

right on the money, junkie! my dad uses one of these on occasion when he's doing a/c work. its cheap and it works okay, but it takes a lot of air.

btw, pick up a manifold/gauge set form harbor freight if you are doing a/c work.

 

[TrexMex]

thanks for the replies guys, I guess my whimpy 3 gallon, 1HP oil-lubed crafstman compressor won't cut it .... I do have access to a shop compressor at a friend's shop though, and considering I need to spend around 400 dlls on a new compressor, condenser, accumulator and flush stuff I think I'll go that direction until I can spend on a decent vacuum pump. BTW I've seen a lot of different CFM capacities out there... would the smallest (cheapest) 1.5 CFM pump do?

Thanks for the heads up on the manifold/gauge set kunar, will follow the advice

 

[4x4junkie]

Vacuum CFM isn't really important, it's the depth of the vacuum that counts. Even a 0.5 CFM pump theoretically would work if it can produce a good deep vacuum (at least 29.5 in-Hg or better at sea level), you'll just have to run the pump a few minutes longer is all.

Yeah, that compressor won't work for sure. Mine is a 5HP comp and the best it could maintain was about 95-100 PSI (close, but just not quite enough. The vacuum was only about 28in-Hg at that pressure, which is just short of what's needed to boil any moisture out effectively).

 

[TrexMex]

Vacuum CFM isn't really important, it's the depth of the vacuum that counts. Even a 0.5 CFM pump theoretically would work if it can produce a good deep vacuum (at least 29.5 in-Hg or better at sea level), you'll just have to run the pump a few minutes longer is all.

Yeah, that compressor won't work for sure. Mine is a 5HP comp and the best it could maintain was about 95-100 PSI (close, but just not quite enough. The vacuum was only about 28in-Hg at that pressure, which is just short of what's needed to boil any moisture out effectively).

So when you put the terms "vacuum", "sea level" and "boiling point" in the same sentence it all fell into place (psychrometrics!!!!).... We're below sea level here so there is absolutely no way I will get the required vacuum (32+ in-Hg) to effectively evacuate the system with that kind of pump... guess I'll have to spend an extra 100 bucks on a decent vacuum pump....

Good still I'm still single, at least for another 2 months...

 

[TrexMex]

Speaking of flushes... Found out my low pressure port leaks, so I need a new hose assembly.... can I get a junk yard one or should I get a new one? Can I flush it given that the low pressure side has some sort of a "canister"? would this be a filter?

I know I'm asking a lot of questions but I just refuse to take it to a shop.... Been dancing around with several shops and never found one that would do a decent job....

thanks again guys

 

[4x4junkie]

The low pressure fitting is on the accumulator (drier). You should be replacing that anyway.

And as for needing 32in-Hg, WTF? What are you like a mile underground or something??? I thought the lowest place on the North American continent was Death Valley at a mere 282 feet below, in which case this would only add about 0.2in-Hg to the requirement (which should be within the capability of such a pump if it's hooked to a good compressor).

Edit:
Maybe you meant the high-pressure port, which is on the discharge hose? You might be able to replace just the valve core if that's the case. Make sure it's an A/C fitting valve core though (tire valve cores won't work).

 

[TrexMex]

yeah I think I exaggerated for a tad bit there, huh? (I work better in psi!!!) we're around -60 ft over here.... I'll get the pump tomorrow and test it and will let you know of the result..

Sorry I meant high pressure hose, which is the one leaking... Can I replace r134a valve cores? And, to add to that, what is the in-line can-shaped part of the hose? pic here: http://www.therangerstation.com/tech_library/4L_Conversion.html

 

[4x4junkie]

I'm guessing you're speaking of the "muffler" on the discharge hose (between the compressor and the high-side port). There should be a high-pressure cutout switch mounted on the underside of it.
It's not essential for A/C operation, although I'm not sure how effectively it can be flushed out. If the hose is original, I'd just get a new one for it (I recently had to replace the one on my '94 due to age).

 

[HareRazor]

I used one of those harbor freight vacuum pumps on my Ford Contour, and it pulled it down, but it took a long while for it to suck it down.

 

[TrexMex]

I'm guessing you're speaking of the "muffler" on the discharge hose (between the compressor and the high-side port). There should be a high-pressure cutout switch mounted on the underside of it.
It's not essential for A/C operation, although I'm not sure how effectively it can be flushed out. If the hose is original, I'd just get a new one for it (I recently had to replace the one on my '94 due to age).

I was thinking about replacing the hose, damn thing looks ugly and rusted.... and somehow I imagined that thing would be some kind of noise suppresion device...

After all this it better cool like I'm in the middle of winter in WI!!!!

Thanks again man!! You've been veery patient answering all my AC noob questions