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I Have Questions About Air Compressors for Knowledgeable Persons

Make_My_DayMake_My_Day Senior MemberPosts: 7,863 Senior Member
edited May 13 in Clubhouse #1
I have a 3-4 years old Kobalt portable air compressor that has an 8 gallon tank, and will put out about 140 PSI pressure to the tank, and cost about $125. It worked fine up until about 6 months ago. When I first turn it on when I need compressed air it works fine and builds air pressure to what I have it set for maximum. Once it shuts off and I use some of the pressure stored in the tank, it won't restart until it sits for a while and I have turned off the power switch. Once it starts to work again, it goes through the same cycle all over again and fails to work once full pressure is reached.
I realize that these machines are cheap Chinese garbage and you can't expect much of a lifespan out of them, but damn, something like this should work for years before having to junk it and start over again.
I figure the malfunction is in the Pressure Switch, and is why the compressor won't restart after a one-time use. If I could actually find the part and replace it, I probably would have a working compressor again, but noooooo, the compressor is considered to be "obsolete" and no parts are available for it. It's a real shame that an otherwise functional compressor won't work without a $45 part, and there are none to be had.
My #1 question is: is there a workaround for this by trying to substitute a pressure switch from another model, or would it be possible to eliminate the switch out of the circuit, and regulate the pressure manually?
My #2 question is: If repair is not possible, can someone that uses a compressed air machine often and may have experience with multiple brands of air compressors recommend a brand other than Kobalt that might last longer than this Lowes junk I bought. I want to pay between $125 and $150 for it. I can go for a little more if the recommended machine has an excellent longevity period attached to the brand.
JOE MCCARTHY WAS RIGHT:
THE DEMOCRATS ARE THE NEW COMMUNISTS!

Replies

  • zorbazorba Senior Member Posts: 24,595 Senior Member
    To the best of my knowledge, a pressure switch is a pressure switch. If its rated for the correct pressure range and you can plumb/wire it in safely, you should be GTG. I wouldn't run it manually...
    -Zorba, "The Veiled Male"

    "If you get it and didn't work for it, someone else worked for it and didn't get it..."
  • Make_My_DayMake_My_Day Senior Member Posts: 7,863 Senior Member
    edited May 13 #3
    Thanks Zorba. I kinda figured that, but I needed some info from someone with more knowledge about electrical devices than I have. I'll need to visually and specs match the original with one that is available on the internet.
    JOE MCCARTHY WAS RIGHT:
    THE DEMOCRATS ARE THE NEW COMMUNISTS!
  • TugarTugar Senior Member Posts: 2,350 Senior Member
    Zorba is correct. It's just a pressure switch. I also backup his warning. Running one manually is a very bad idea. 

    On a side note, I have always wanted to build a Volks Air compressor conversion on an  aircooled VW engine. LOTS of air. 
     

    http://www.dunnrightinc.com/


    Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery.
    Winston Churchill
  • JustsomedudeJustsomedude Posts: 996 Senior Member
    Zorba is correct. They're usually a two wire, 1/4"npt fitting. Find one from a common brand and swap it out. Polarity shouldn't matter either. If you get a new compressor, more CFM trumps all other specs. 
    We've been conditioned to believe that obedience is virtuous and voting is freedom- 
  • VarmintmistVarmintmist Senior Member Posts: 7,654 Senior Member
    As to a good compressor, you wont buy one for 125.00. I have my fathers old Black Max (Sanborn, not made anymore) oil lubed compressor. I got rid of the Craftsman I had and wont go back to a air cooled unit ever if I manage to break this one.
    As was stated, CFM is your friend.

    As a question, are you draining the storage after use? If not, then the sw may be a victim of moisture.
    It's boring, and your lack of creativity knows no bounds.
  • Make_My_DayMake_My_Day Senior Member Posts: 7,863 Senior Member
    Thank you for your answers. Yeah, I realize $125 is not enough for a "good" compressor. I was speaking relatively good, compared to other $125 models. If 125-150 $$ won't buy a "good" one, then I'm looking for the best one I can get for that amount of money (if there is such a thing) I am a fan of quality, but I have to be practical about it for the time being. My usage doesn't justify $500 or more for a compressor right now. Maybe down the road. I have made my shed into a small welding shop. I want to be able to use the compressor for air tools and possibly for plasma cutting one day.
    It is possible that moisture made the switch fail. I have been rather lax about that, because I didn't use the unit much, so it didn't occur to me to drain the tank every time. For now, I would be satisfied if I could get one that is a bit better quality than Kobalt, if I don't end up switching out the switch. I definitely will have to be more careful about draining the tank more often. That's probably a major fail on my part.
    JOE MCCARTHY WAS RIGHT:
    THE DEMOCRATS ARE THE NEW COMMUNISTS!
  • zorbazorba Senior Member Posts: 24,595 Senior Member
    Get an oil lubed one if you have to buy another...
    -Zorba, "The Veiled Male"

    "If you get it and didn't work for it, someone else worked for it and didn't get it..."
  • kansashunterkansashunter Senior Member Posts: 1,899 Senior Member
    My experience with pressure switches is they either work or not. I am wondering if there is some crud not letting the pressure bleed off the switch. You can take the cover off and see if the contacts are moving or not. If they aren't I would take it off and clean out the bottom and wherever it screws into. If the contacts are moving but it is not kicking on you can file them if they aren't burnt up. All that said be careful, with the cover off there is power there and if there is crud keeping it from restarting it could get to where it won't shut off, bad juju. I would want to fix it soon or watch the pressure gauge and make sure it doesn't build too much pressure.  
  • Make_My_DayMake_My_Day Senior Member Posts: 7,863 Senior Member
    edited May 14 #10
    I almost had the problem solved, but I did find out it's definitely the pressure switch. I took the plastic housing off it today, and managed to find where the pressure switch was. It is screwed directly into the air storage tank. There are no visible contacts on it other than the wires that have standard electrical plugs on it. Apparently the unit functions on 12-24 VDC or 120 VAC. They use these units in air-bag raised cars and trucks and air compressors and other air devices. It looks like an old automotive oil pressure sensing unit. Housing is the nut for screwing it in and 2 wires sticking out the bottom. First I opened the drain valve while the pump was running and let all the water and air come out. There was a huge amount of rusty water in there. I let the pump run until all the crud came out and then closed the valve to let the pressure build up. After the pump shut off, I connected a power tool to the air supply and ran it until the compressor started running again. Then ran the air out once again and the compressor continued to refill the tank. I thought it was resolved, but after a while the compressor stopped running again. Then I took the pressure switch out and it was very dirty with caked on rust. I cleaned off the rust, poked a narrow spring in the hole and cleared out any debris that was inside the switch, and and reinstalled the switch. The compressor filled the tank for one cycle and quit restarting. That was it. I took the pressure switch out and there were numbers and pressure settings on it that I could refer to if I could find a parts supplier for it. I found the company that made them (In Taiwan of course), but they no longer had that model number available. Eventually I found aftermarket replacement switches on Ebay and Amazon. I got a 2-pack from Amazon with the same specs as the OEM one for $13. They will arrive Saturday, and hopefully this will solve the problem.
    JOE MCCARTHY WAS RIGHT:
    THE DEMOCRATS ARE THE NEW COMMUNISTS!
  • knitepoetknitepoet Senior Member Posts: 22,202 Senior Member
    my only suggestion is pay VERY close attention to the pressure gauge when you're testing your repair.

    You already know you have some rust damage inside the tank.
    Seven Habits of Highly Effective Pirates, Rule #37: There is no “overkill”. There is only “open fire” and “I need to reload”.


  • Make_My_DayMake_My_Day Senior Member Posts: 7,863 Senior Member
    The new ones are 115-145 PSI, which is 5 PSI lower than the OEM part, but I will keep an eye on it until I'm satisfied that it works close to the specs of the original. Yeah, I will be draining the tank regularly from now on.
    JOE MCCARTHY WAS RIGHT:
    THE DEMOCRATS ARE THE NEW COMMUNISTS!
  • zorbazorba Senior Member Posts: 24,595 Senior Member
    You may want to consider an automatic drain dingus.
    -Zorba, "The Veiled Male"

    "If you get it and didn't work for it, someone else worked for it and didn't get it..."
  • Make_My_DayMake_My_Day Senior Member Posts: 7,863 Senior Member
    edited May 14 #14
    zorba said:
    You may want to consider an automatic drain dingus.

    Is that something you can add on? I have only seen the ones with a manual drain valve on the bottom.
    JOE MCCARTHY WAS RIGHT:
    THE DEMOCRATS ARE THE NEW COMMUNISTS!
  • Make_My_DayMake_My_Day Senior Member Posts: 7,863 Senior Member
    The pressure switch was the problem. It works now, so thanks for the help to everyone that responded.
    JOE MCCARTHY WAS RIGHT:
    THE DEMOCRATS ARE THE NEW COMMUNISTS!
  • zorbazorba Senior Member Posts: 24,595 Senior Member
    zorba said:
    You may want to consider an automatic drain dingus.

    Is that something you can add on? I have only seen the ones with a manual drain valve on the bottom.
    Yes. There's a bunch of different kinds that work in different ways. There's even 12 volt ones. But they're not cheap.
    -Zorba, "The Veiled Male"

    "If you get it and didn't work for it, someone else worked for it and didn't get it..."
  • Make_My_DayMake_My_Day Senior Member Posts: 7,863 Senior Member
    Now that I know what caused the problem I'll be more attentive to draining the tank after use.
    JOE MCCARTHY WAS RIGHT:
    THE DEMOCRATS ARE THE NEW COMMUNISTS!
  • VarmintmistVarmintmist Senior Member Posts: 7,654 Senior Member
    You need to drain the tank every time because rust will compromise the integrity of the tank.

    It's boring, and your lack of creativity knows no bounds.
  • Make_My_DayMake_My_Day Senior Member Posts: 7,863 Senior Member
    You need to drain the tank every time because rust will compromise the integrity of the tank.


    Yeah, I am familiar with that need to drain it, wasn't doing it often because of the little use I was giving it. I'll be sure to take care of it more often now.
    JOE MCCARTHY WAS RIGHT:
    THE DEMOCRATS ARE THE NEW COMMUNISTS!
  • JaphyJaphy Posts: 140 Member
    I have a small Porter Cable compressor. I have repaired the pressure switch multiple times. Always happens during the AZ monsoon season when the humidity is high and there is water from condensation in the tank. Moisture shorts the pressure switch. Remove the switch dry it with a hair dryer. 
    Open the bleed valve on the bottom of the tank when not in use that usually blows all the water out of the tank. 
  • Make_My_DayMake_My_Day Senior Member Posts: 7,863 Senior Member
    Japhy said:
    I have a small Porter Cable compressor. I have repaired the pressure switch multiple times. Always happens during the AZ monsoon season when the humidity is high and there is water from condensation in the tank. Moisture shorts the pressure switch. Remove the switch dry it with a hair dryer. 
    Open the bleed valve on the bottom of the tank when not in use that usually blows all the water out of the tank. 

    Yeah, that seems to be the issue with mine. I live in Florida, where moisture is always a problem between March and December. I will start leaving the valve open from now on too, while not in use.
    JOE MCCARTHY WAS RIGHT:
    THE DEMOCRATS ARE THE NEW COMMUNISTS!
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