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air conditioner pump use as compressor

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  • MattiJ
    replied
    Originally posted by darryl View Post
    I wonder how the capacity compares- if this one I have now is a 2 ton, what does that make a fridge compressor- 1/4 ton?
    Something like that.

    I got also 2 rotary compressors for "some project", I'm kind of curious to see how good vacuum the rotary/scroll compressor can pull. (Turns out out one of them was actually inverter driven permanent magnet synchronous motor and very much useless.)

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  • darryl
    replied
    Well, this is a 'tower' type, a 2 ton I believe. Looks like the capacitor is a two section, and one section is for the pump. There is a relay, but it appears to be on/off only and nothing is there to switch a start winding in or out, unless it's internal.

    In years past I did use fridge compressors for air and for vacuum. They were slow on both counts. I expect this unit will be much quicker. I wonder how the capacity compares- if this one I have now is a 2 ton, what does that make a fridge compressor- 1/4 ton?

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  • R_Audano
    replied
    When I was younger and essentials didnt include a new compressor I used a 2-cylinder Thermo King compressor for my air compressor. The cycle time on a 100 gallon tank was approx 6 minutes from 90 - 125. While it worked... I needed more. The problem was the intake was ported so in keeping with Detroit Diesels supercharger theory, I turned a flat pulley for a smog pump and used it for a belt tensioner. then used the output from the smog (AIR) pump to supercharge the compressor. It cut my cycle time in less than half and finally retired the pump 15 years later when i found a nice Quincy pump. I ran straight up 30wt. non-detergent oil in the crankcase.

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  • Andre3127
    replied
    Originally posted by Sparky_NY View Post
    Judging by the dimensions you guessed at, that is a very small compressor, far smaller than the typical 2-3 ton air conditioner scroll compressors. As such, I wouldn't expect it to pump much air at all.
    It fills my three gallon tank to 120 psi (I rarely need it that high, I just use it with a blowgun) in a few minutes. The original piston pump could fill it faster, but it was broken and probably a lot louder.

    If any significant air volume is required I'll fire up the 60 gallon or pancake. Also have a hotdog style but that's on permanent loan for the time being.

    Just something nice and quiet to use to blow oil out of a tapped hole or something. It cost me nothing to build so I can't complain. The tank was found on the side of the road.

    Sent from my XT1053 using Tapatalk

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  • Sparky_NY
    replied
    Originally posted by Andre3127 View Post
    It's about 4" in diameter and 9" tall if I had to guess. And yes, I tipped mine over.... lots of mineral oil came out. I don't move mine around because of the potential mess factor.

    Sent from my XT1053 using Tapatalk
    Judging by the dimensions you guessed at, that is a very small compressor, far smaller than the typical 2-3 ton air conditioner scroll compressors. As such, I wouldn't expect it to pump much air at all.

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  • Andre3127
    replied
    Originally posted by Sparky_NY View Post
    If by a "tower" you mean a cylinder, maybe 8 inches diameter and about a foot and a half tall, that is a scroll compressor. Anyone that thinks there isn't much oil in one, has not had to clean it up when a junk unit is tipped on its side! As for the oil in the lines, there is indeed oil that circulates in the lines, its returning to the compressor is very important for proper AC operation. If the evaporator and condenser are separated by 20ft or more vertically, its common practice to put a trap at the evap to promote oil return to the compressor. I had a customer that had 4 compressors changed in about 3 years, thats insane, the reason was no trap at the evaporator and the condenser was on the roof, 3 stories up. After I installed the trap, and a new compressor, its been 4 years now and working fine. There are a LOT of people that think they know the refrigeration trade out there.

    Inverter driven compressors are extremely rare except on mini split systems.
    It's about 4" in diameter and 9" tall if I had to guess. And yes, I tipped mine over.... lots of mineral oil came out. I don't move mine around because of the potential mess factor.

    Sent from my XT1053 using Tapatalk

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  • Sparky_NY
    replied
    Originally posted by Andre3127 View Post
    I'm not sure what it's called exactly... It's shaped like a tower, and not a bubble like a fridge compressor.

    Sent from my XT1053 using Tapatalk
    If by a "tower" you mean a cylinder, maybe 8 inches diameter and about a foot and a half tall, that is a scroll compressor. Anyone that thinks there isn't much oil in one, has not had to clean it up when a junk unit is tipped on its side! As for the oil in the lines, there is indeed oil that circulates in the lines, its returning to the compressor is very important for proper AC operation. If the evaporator and condenser are separated by 20ft or more vertically, its common practice to put a trap at the evap to promote oil return to the compressor. I had a customer that had 4 compressors changed in about 3 years, thats insane, the reason was no trap at the evaporator and the condenser was on the roof, 3 stories up. After I installed the trap, and a new compressor, its been 4 years now and working fine. There are a LOT of people that think they know the refrigeration trade out there.

    Inverter driven compressors are extremely rare except on mini split systems.

    Leave a comment:


  • A.K. Boomer
    replied
    Years ago one of my bro's threw a GM style car comprendo on an old lawnmower base and hooked a motor to it,

    it was a duel piston self contained lower end so had it's own oil res.

    we used that thing for years - could not kill it, it had no tank - was just direct air for pumping up tires and stuff, and you could use it as an air nozzle some as when you stopped the end with it's shut off valve it would labor and build up quite a bit of pressure, you also had to have that closed to fill tires - had two lines one with the shut off and the other with the tire filler end,

    thing was very funky and made a funny sound when working but my Dad loved it and was actually proud of it cuz my bro threw it together as a kid.

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  • Andre3127
    replied
    Originally posted by MattiJ View Post
    Centrifugal? Not rotary or scroll?

    In OP's case I would try to change the oil to normal air breathing compressor oil.
    And you have a problem if the compressor happens to be one of the newer pm synchronous motor/ inverter combos. Those wont run without inverter electronics and to trick the inverter board to work might turn out really tricky.
    I'm not sure what it's called exactly... It's shaped like a tower, and not a bubble like a fridge compressor.

    Sent from my XT1053 using Tapatalk

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  • Planeman41
    replied
    Back in the mid 1950s when I was a teenager building model airplanes I rigged up a refrigerator compressor to operate an air brush. As it had a starting coil, I had two switches side by side to turn it on, one for the starting coil, the other for running. I flipped both switches on together to start the compressor and immediately switched off the starting coil. Worked like a charm!

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  • Tim Aldrich
    replied
    Go look up Halligan142 on YouTube. He made a compressor out of a refrigerant pump. His day job is a heating/air conditioning tech so he knows what he's doing.

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  • winchman
    replied
    I used the compressor from an old refrigerator as a vacuum pump for several years. The electrical connection was at the top, so I put the compressor in a tub of water to keep it cool. There was only a tiny bit of oil coming out the discharge side, but I'd put a little oil in the vacuum line each time I used it.

    It worked fine for evacuating the DIY auto AC systems I installed back in the '70s.

    Leave a comment:


  • darryl
    replied
    As far as changing the oil, I can see no way to do that aside from turning the unit on its side with one of the copper tubes at the low point. Both tubes are on the same side of the unit, so either one might pour out oil. There's no way of knowing if all the oil can be extracted and the exact amount of a replacement oil determined.

    There was no circuitry on the thing at all, just a point where the ac line came in and went to the relay with all it's terminals. I don't know if the fan motor is 220 or whether it gets 110 by means of a neutral wire. I'll have to decypher the wiring.
    Last edited by darryl; 05-16-2017, 12:26 AM.

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  • darryl
    replied
    As far as I know, compressors like that recirculate their own oil- I doubt that much oil at all circulates through the system. It would seem to be a hindrance to cooling and probably difficult to keep from collecting just where you don't want it.

    There was no oil in the lines that I cut to remove it from the base, and no oil in the tank-like thing that's inline with one of the pipes. No evidence of oil in the condenser, at least none leaking out regardless of the angle I held it at.

    Now I have to determine if the capacitor in there was meant for the compressor or for the fan motor.

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  • JoeLee
    replied
    You won't get much volume out of it. When I was a kid the guy down the street made an air compressor out of one. It took almost a half hour to get enough pressure in a 50 gal propane tank to fill my bicycle tires.

    JL....................

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