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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / September 2006A/C - electric vacuum pump purchase
I have a question for the air condition repairmen in this group... I need to buy an electric vacuum pump for my DIY car projects. I am a car repair hobbyist, do not have the shop air compressor. The pump can be small (1/6-1/3 hp) but should be nicely designed and must be reliable. I do not want to buy junk :-) What manufacturer/model could you recommend around $200? Which features are important to check when buying a pump? p.s. Are there pump on the market with fittings for R134 and R22 ? > I have a question for the air condition repairmen in this group... > [quoted text clipped - 9 lines] > p.s. > Are there pump on the market with fittings for R134 and R22 ? If you're handy with a soldering iron, just buy a cheap used refrigrerator and remove its compressor. Solder a refrigerant fitting ont he suction line, and presto- vacuum pump for $20 or thereabout. Just remember to feed it a teaspoon or two of refrigerant oil (use the mineral type for R-12 or R-22)into the suction line with it running every few hours of use. >> I have a question for the air condition repairmen in this group... >> [quoted text clipped - 17 lines] > mineral type for R-12 or R-22)into the suction line with it running every > few hours of use. I'll second that motion. I used those for several decades--actually one is still in use that I made in the 70's--and they do a nice, quiet job. You may first want to do a little research to determine one that will be faster than others. If you wish it to look more 'presentable', you might make a small hand-truck to fit it & roll it around on. I did that and did the same thing on my 120-amp battery charger made from a washing machine motor and an alternator-with-regulator. Both were small, compact, portable, and self-supporting around the cars. s >> If you're handy with a soldering iron, just buy a cheap used refrigrerator >> and remove its compressor. Solder a refrigerant fitting ont he suction [quoted text clipped - 12 lines] > motor and an alternator-with-regulator. Both were small, compact, portable, > and self-supporting around the cars. s Great ideas guys, but I was looking for tips when buying a vacuum pump. I have a $200 budget for the pump and do not need to play with refridgerators. I need to know if I can buy a pump with some kind of oil filter, is it worth it to pay for dual stage one or not, etc... I like the DIY solution with the refridgerator compressor, but there will be considerable work involved in looking up fittings, assembling it in some fixture, taking care of oil consumption or filtering the output/vent - this is discouraging enough... That is why I want to shell out some money and buy a real thing. Pszemol Wrote: > >> If you're handy with a soldering iron, just buy a cheap used > refrigrerator [quoted text clipped - 36 lines] > or filtering the output/vent - this is discouraging enough... > That is why I want to shell out some money and buy a real thing. The links I posted has the pump with kits but look around on the web page they should have pumps seperate. And as said they can answer all questions you may have on the pumps. Good Luck MT  SignatureMT-2500 http://www.automotiveforums.com >I like the DIY solution with the refridgerator compressor, but >there will be considerable work involved in looking up fittings, Sorry.. I thought you were just poor. I didn't realize you were poor and lazy. Steve B. >>I like the DIY solution with the refridgerator compressor, but >>there will be considerable work involved in looking up fittings, > > Sorry.. I thought you were just poor. > I didn't realize you were poor and lazy. ??? What was that, Steve ? Do you have some problem when people do not take your advice ? I said I like you idea to make a "getto pump", but I stated at the begining that I can afford buying one from the store... No need to play meanie, Steve! :-) >>> If you're handy with a soldering iron, just buy a cheap used >>> refrigrerator and remove its compressor. Solder a refrigerant fitting [quoted text clipped - 20 lines] > I need to know if I can buy a pump with some kind of oil filter, > is it worth it to pay for dual stage one or not, etc... Just buy one from a reputable brand name and forget all that. You don't need multi-stage pumps for evacuating AC systems. They don't have oil filters (or filters of any kind). The oil should be changed periodically in any of them, because vacuum pump oil becomes contaminated with moisture. > Just buy one from a reputable brand name and forget all that. > You don't need multi-stage pumps for evacuating AC systems. OK, but if a dual stage pump is cheaper than single stage ? > They don't have oil filters (or filters of any kind). I was thinking of some kind of oil blockage on the outtake and some check valve on the intake to prevent loosing vacuum and contaminating target system with pup's oil when pump is turned off. But I guess this can be achived with closing a cut off valve before shuting off the pump, right ? > The oil should be changed periodically in any of them, > because vacuum pump oil becomes contaminated with moisture. Get it. Thanks. BTW - Is "Steve" <no@spam.thanks> the same person as "Steve B." <none@none.com>? Steve B. sounds like a real jerk, but Seve with no B is very helpful - thanks! >> Just buy one from a reputable brand name and forget all that. >> You don't need multi-stage pumps for evacuating AC systems. [quoted text clipped - 6 lines] > and some check valve on the intake to prevent loosing vacuum > and contaminating target system with pup's oil when pump is turned off. Most vacuum pumps have check valves as part of their design. There's usually an expansion chamber that traps oil droplets and allows them to return to the sump, not a filter. Pszemol Wrote: > I have a question for the air condition repairmen in this group... > [quoted text clipped - 9 lines] > p.s. > Are there pump on the market with fittings for R134 and R22 ? Fittings can be change to what ever you need as long as you have the right hose connect to the system. Links below have some. Also the ACkits.com has a air cond repair forum that can help you on your questions and problems on AC repair. Good luck MT http://tinyurl.com/jt94c http://tinyurl.com/qvn5k http://tinyurl.com/q2h9j SignatureMT-2500 http://www.automotiveforums.com > Fittings can be change to what ever you need as long as you > have the right hose connect to the system. How the pump is influenced with a residue of the refridgerant left in the system before vacuuming it ? Will the switching the pump between R134 and R22 systems do any bad things to the vacuum pumps, its o-rings, seals, etc ? > Links below have some. > Also the ACkits.com has a air cond repair forum that can help you on [quoted text clipped - 7 lines] > > http://tinyurl.com/q2h9j Thanks. I can find many pumps - the point is to choose the right one. And this task is what I needed help with... Pszemol Wrote: > > Fittings can be change to what ever you need as long as you > > have the right hose connect to the system. [quoted text clipped - 18 lines] > Thanks. I can find many pumps - the point is to choose the right one. > And this task is what I needed help with... As said ackits.com has a good AC forum with the best AC people from all over the world. Run a post on it and they will be glad to help you. http://www.autoacforum.com/ Good Luck MT SignatureMT-2500 http://www.automotiveforums.com > > Fittings can be change to what ever you need as long as you > > have the right hose connect to the system. > > How the pump is influenced with a residue of the refridgerant > left in the system before vacuuming it ? It's not. This has been done for years without problems. > Will the switching the pump between R134 and R22 systems do > any bad things to the vacuum pumps, its o-rings, seals, etc ? Thought you were doing automotive? Where does the R-22 come into the picture? Switching between refrigerants is not a problem. As long as you maintain the vacuum pump (basically oil changes) you'll be fine. > > Links below have some. > > Also the ACkits.com has a air cond repair forum that can help you on [quoted text clipped - 10 lines] > Thanks. I can find many pumps - the point is to choose the right one. > And this task is what I needed help with... Robinaire, Mastercool, and Inficon all make very good vacuum pumps. Pick the highest CFM and the lowest micron rating that fits your budget. To service properly, you need to draw a deep vacuum, 500 microns is your target so, you want a vacuum pump that rated at least that good to begin with. I'd also budget for a micron gauge so you -actually- know that you've pulled a deep vacuum. > Robinaire, Mastercool, and Inficon all make very good vacuum > pumps. I will look for that manufacturers - so far I found really popular in stores (and cheap one - about $120+S&H): FJC 6908 http://www.fjcinc.com/FJCVacuumPump.htm Two stage, 70 microns, 2,5 CFM, 1/4 HP 120AC motor. Any personal experience with that pump in the group ? Is it something worth considering or is it a cheapo "made in china" ? > Pick the highest CFM and the lowest micron rating that fits your > budget. How microns translate to inches of mercury ? I am not sure how to compare one pump rated at 28 inHg and one rated 70 microns... Which one is better and how much better ? > To service properly, you need to draw a deep vacuum, 500 microns > is your target so, you want a vacuum pump that rated at least > that good to begin with. Is that 500 microns a requirement stated by the car manufacturer repair manual or something you come up based on your own experience ? > I'd also budget for a micron gauge so > you -actually- know that you've pulled a deep vacuum. I was guessing the standard A/C pressure gauges will be good enough for the job... Good idea. > > Robinaire, Mastercool, and Inficon all make very good vacuum > > pumps. [quoted text clipped - 6 lines] > Any personal experience with that pump in the group ? > Is it something worth considering or is it a cheapo "made in china" ? Sorry, not familiar with that brand. > > Pick the highest CFM and the lowest micron rating that fits your > > budget. > > How microns translate to inches of mercury ? Atmospheric pressure equals (appx) 760,000 microns. if we divide 760,000 by 29.9, we get 25,418, so one inch of mercury equals 25,418 microns. To attempt to use a standard manifold gauge set vacuum gauge to assess vacuum is akin to trying to measure crankshaft main bearing clearance with a yard stick. > I am not sure how to compare one pump rated > at 28 inHg and one rated 70 microns... > Which one is better and how much better ? A pump rated at 28 in.hg. is basically worthless, a waste of time. A pump rated at 70 microns is probably a laboratory piece. > > To service properly, you need to draw a deep vacuum, 500 microns > > is your target so, you want a vacuum pump that rated at least > > that good to begin with. > > Is that 500 microns a requirement stated by the car manufacturer > repair manual or something you come up based on your own experience ? It's the standard for the AC industry. > > I'd also budget for a micron gauge so > > you -actually- know that you've pulled a deep vacuum. > > I was guessing the standard A/C pressure gauges > will be good enough for the job... Good idea. For most people and most repair shops, it is. My view; it's better to spend $250 on a vacuum pump plus $150 on a micron gauge and be certain that the moisture has been evacuated and there are no leaks versus spending $400 on a vacuum pump and wonder. You can pull XX.X vacuum where water will boil in the system, but it takes a much deeper vacuum to actually remove the moisture. >> I will look for that manufacturers - so far I found really >> popular in stores (and cheap one - about $120+S&H): [quoted text clipped - 5 lines] > > Sorry, not familiar with that brand. OK. >> > Pick the highest CFM and the lowest micron rating that fits your >> > budget. [quoted text clipped - 4 lines] > if we divide 760,000 by 29.9, we get 25,418, so one inch of > mercury equals 25,418 microns. Cool. So microns are just 1/1000 of milimeters of mercury... 1/1000 of Torr. Or 1 umHg :-) Got it. Now it is simple :-)) http://en.wikipedia.org/wiki/Torr Thanks. > To attempt to use a standard manifold gauge set vacuum gauge to > assess vacuum is akin to trying to measure crankshaft main > bearing clearance with a yard stick. But most of the car repair shops just use them on day to day basis. >> I am not sure how to compare one pump rated >> at 28 inHg and one rated 70 microns... >> Which one is better and how much better ? > > A pump rated at 28 in.hg. is basically worthless, a waste of time. > A pump rated at 70 microns is probably a laboratory piece. 70 microns is the rating of this $120 pump I found and listed above. >> > To service properly, you need to draw a deep vacuum, 500 microns >> > is your target so, you want a vacuum pump that rated at least [quoted text clipped - 4 lines] > > It's the standard for the AC industry. Cool. Thanks. Do they specify for how long time this 500 microns (1/2 mmHg) pressure should be applied to the system? >> > I'd also budget for a micron gauge so >> > you -actually- know that you've pulled a deep vacuum. [quoted text clipped - 10 lines] > You can pull XX.X vacuum where water will boil in the system, but > it takes a much deeper vacuum to actually remove the moisture. Can deeper vacuum be substituted with longer vacuuming time ? If water boils, it only takes time for it to fully evaporate. > Cool. > So microns are just 1/1000 of milimeters of mercury... > 1/1000 of Torr. Or 1 umHg :-) Got it. Now it is simple :-)) > http://en.wikipedia.org/wiki/Torr Thanks. You got it! > > To attempt to use a standard manifold gauge set vacuum gauge to > > assess vacuum is akin to trying to measure crankshaft main > > bearing clearance with a yard stick. > > But most of the car repair shops just use them on day to day basis. Yes, and that is not a good thing. You gearing up to do your own work gives you the opportunity to take it up a notch. > > A pump rated at 28 in.hg. is basically worthless, a waste of time. > > A pump rated at 70 microns is probably a laboratory piece. > > 70 microns is the rating of this $120 pump I found and listed above. Sounds good then. > > It's the standard for the AC industry. > > Cool. Thanks. Do they specify for how long time this > 500 microns (1/2 mmHg) pressure should be applied to the system? There is no time standard for 500 microns, when you reach it, you have removed as much of the moisture as is needed. The micron gauge replaces vacuuming to a time standard. Vacuum to 500 microns, shut off vacuum pump, isolate, if the micron gauge holds below 750, you're good to go. > > My view; it's better to spend $250 on a vacuum pump plus $150 on > > a micron gauge and be certain that the moisture has been [quoted text clipped - 4 lines] > > Can deeper vacuum be substituted with longer vacuuming time ? The only way to know is to check against a vacuum gauge of sufficient accuracy. > If water boils, it only takes time for it to fully evaporate. That's not necessarily true, and still doesn't address whether there is still anything leaking. The micron gauge covers that. >> Fittings can be change to what ever you need as long as you >> have the right hose connect to the system. [quoted text clipped - 3 lines] > Will the switching the pump between R134 and R22 systems do > any bad things to the vacuum pumps, its o-rings, seals, etc ? No. Unlike the compressor in an AC system, a vacuum pump doesn't depend on the refrigerant to CIRCULATE the oil. So it can use a mineral base oil that won't be damaged by any of the refrigerants normally used. The problem is that in a system where the refrigerant has to actually carry the oil, you have to use special oils that sometimes are sensitive to chlorine-containing refrigerants. > I have a question for the air condition repairmen in this group... > [quoted text clipped - 9 lines] > p.s. > Are there pump on the market with fittings for R134 and R22 ? I know nothing about vac pumps BUT I see all kinds of them in pawn shops in the industrial side of town. Seems like every pawn shop has 5 or 6. Some with tanks meant for a/c work and some meant for ???. |
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