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  • help......compressor won't start!

    Just got a call from one of my crews......
    They are using a Porter Cable twin stack compressor. It is set to come on at 110lbs. Often the pressure is dropping below 110 before the compressor kicks in. This is causing problems as the nails are not fully driving.
    Is there something they could do in the field to fix this? I don't know much about how the regulator switch works. I had them try adjusting the set point higher. They said it is still dropping to low for nailing before the compressor kicks in.
    Thanks.....Ray

  • #2
    Re: help......compressor won't start!

    If it fails to start up, you will need to obtain and install a new pressure switch. Depending on how handy all of you are Square D makes many pressure switches for water pumps and air compressors. Industrial supply houses, electrical distributors and plumbing suppliers will either have them or can get them for you. If you are setup to do business with WW Grainger they have lots to select from.

    If you aren't comfortable doing your own repairs, look in the yellow pages under "Compressors - Air & Gas" and make a few calls. A place that services small industrial and/or portable air compressors should be able to replace the pressure switch easy. As a last resort find a factory Dewalt / Porter-Cable service center. They should be able to do it for sure.
    Last edited by Woussko; 08-19-2008, 08:42 AM.

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    • #3
      Re: help......compressor won't start!

      Question: Does it try to start but the motor just goes GRRRRR and won't budge or is nothing happening at the set start pressure?

      Comment


      • #4
        Re: help......compressor won't start!

        Originally posted by Woussko View Post
        If it fails to start up, you will need to obtain and install a new pressure switch. Depending on how handy all of you are Square D makes many pressure switches for water pumps and air compressors. Industrial supply houses, electrical distributors and plumbing suppliers will either have them or can get them for you. If you are setup to do business with WW Grainger they have lots to select from.

        If you aren't comfortable doing your own repairs, look in the yellow pages under "Compressors - Air & Gas" and make a few calls. A place that services small industrial and/or portable air compressors should be able to replace the pressure switch easy. As a last resort find a factory Dewalt / Porter-Cable service center. They should be able to do it for sure.
        Woussko
        Thanks for the quick reply. The compressor starts, however not until it is well below the set point. This crew is currently at a job site in the mountains. It is at least 50 miles from any kind of service. They are keeping the job going by hand driving the nails the rest of the way in after shooting them with the gun.
        Since it sounds like something is sticking I had hoped maybe it was a problem related to corrosion or whatever that could be at least temporarily fixed by a squirt of oil or scraping or whatever. They tell me the problem is intermitent and part of the time the compressor will kick in at the correct pressure point. They are pretty handy, however when it comes to the pressure switch we have never had one apart, so wouldn't know if it can be done in the field without a new gasket or whatever. They don't want to do something to completely dissable the compressor as it is currently usable to drive nails 80% of the way in.

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        • #5
          Re: help......compressor won't start!

          in most pressure switches there are two adjustments, the max pressure, and the differential (the difference between the start and stop),


          if the motor hums and does not start, until pressure is lowered,

          you could have a bad Unloaded, it is a part between the pump and tank, and it is a unique valve that lets the pump "unload" and release the air out of the head so it can start with out pressure in the pump,

          the other thing is the check valve at the tank, (some times on lower cost machines) the check is built into the unloader,
          Push sticks/blocks Save Fingers
          ~~~~~~~~~~~~~~~~~~~
          "The true measure of a man is how he treats someone who can do him absolutely no good."
          attributed to Samuel Johnson
          ~~~~~~~~~~~~~~~~~~~
          PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

          Comment


          • #6
            Re: help......compressor won't start!

            Originally posted by roadrashray View Post
            Woussko
            Thanks for the quick reply. The compressor starts, however not until it is well below the set point.
            I recommend replacing the pressure switch before trying other things. There is a way to force the compressor to run but due to safety reasons I don't think it's wise to post how to do it here. I don't want anyone getting hurt or worse.

            Do you know the model of your air compressor? If yes, I'll try to see if I can download a parts list and figure out more about it.

            This is only an idea and sometimes may help. Reduce tank pressure to 0 and then remove the pressure switch. You'll have to remove the cover and disconnect the wiring first. TAKE good close-up pictures with the cover off before doing anything more. That way you'll be able to see how to rewire it later on. Anyway once it's removed, try washing the little hole in the fitting on the bottom of the regulator. Dirt or corrosion can build up and prevent the pressure switch from working. Sometimes as insane as this seems, just lots of taps with a small hammer on the pressure switch and especially where the fitting is will shake the dirt out and then things work again. I don't advise tampering with the adjustments. Normally that's not needed except when installing a new one. The main screw with a nut is the Start pressure and the smaller screw is the stop pressure, but they interact. If you change one normally you need to check and set the other. This means lots of starting and stopping. It's best to buy a preset switch where this is factory done.

            If someone is willing to sit and watch the pressure you could wire across the pressure switch but this is really not a safe thing to do. He/she must manually stop and then start the compressor. If he/she left for a few minutes you best hope the safety relief valve opens and vents excess pressure. In addition small air compressors aren't designed or made to run continuously and will overheat.

            OK here comes the bomb: On a job site it's very important to have a backup for any much needed machine or tool in case of failure. Yes, it costs $$$ but over time it pays off.
            Last edited by Woussko; 08-19-2008, 09:43 AM.

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            • #7
              Re: help......compressor won't start!

              Please try this: Take a stick and give the pressure switch about 50 fast smacks but not really hard ones. The idea is to vibrate anything stuck loose but not to bash it to bits. See if that helps. Be sure to pull the plug first.

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              • #8
                Re: help......compressor won't start!

                Originally posted by Woussko View Post
                Please try this: Take a stick and give the pressure switch about 50 fast smacks but not really hard ones. The idea is to vibrate anything stuck loose but not to bash it to bits. See if that helps. Be sure to pull the plug first.
                This may actually work, aim for the nipple that goes from the tank to the Pressure switch itself!

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                • #9
                  Re: help......compressor won't start!

                  then you will need to get a pipe nipple remover, it is so much fun to get those broke off nipples out, expecily if there is some corrosion.
                  Push sticks/blocks Save Fingers
                  ~~~~~~~~~~~~~~~~~~~
                  "The true measure of a man is how he treats someone who can do him absolutely no good."
                  attributed to Samuel Johnson
                  ~~~~~~~~~~~~~~~~~~~
                  PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

                  Comment


                  • #10
                    Re: help......compressor won't start!

                    Originally posted by BHD View Post
                    in most pressure switches there are two adjustments, the max pressure, and the differential (the difference between the start and stop),


                    if the motor hums and does not start, until pressure is lowered,

                    you could have a bad Unloaded, it is a part between the pump and tank, and it is a unique valve that lets the pump "unload" and release the air out of the head so it can start with out pressure in the pump,

                    the other thing is the check valve at the tank, (some times on lower cost machines) the check is built into the unloader,
                    BHD.............They tell me everything operates normally with the exception that the motor does not start most of the time until the pressure has dropped to low for the nail guns to operate correctly. Once the compressor motor starts it continues running to the correct set point. They can initiate a start by disconnecting the hose and dropping the pressure to a lower point which will start the motor and pump the pressure fully which will allow the guns to operate correctly.
                    They had talked with Porter Cable technical service earlier who told them the regulator control unit should be replaced. The reason for my posting is I had hoped the combined experiance of several hundred years on this forum might know of a rube goldberg that would get us back to full song.
                    As luck would have it this problem occured on a day when we were setting the large trusses (50') for this mountain cabin we are building. We are using a rented crane which was only available for today and as I mentioned before this is a remote site without electricity. Normally we would have two compressors at such a job site, but somebody dropped the ball.

                    Comment


                    • #11
                      Re: help......compressor won't start!

                      Just got off the phone with the super on this job. Told me they had 2 compressors until last night. I had forgotten we bought a new Ridgid gas wheelbarrow compressor two weeks ago just for this job. The Porter Cable was the backup.
                      My teeth are knashing right now as the super told me they found the case hardened chain and very expensive pad lock in the back of the truck, however no compressor as the person responsible overlooked using said chain and lock. In the same truck we had two honda generators and a gas water pump which were still there because they were locked. I told him to make the guy walk from the job site to the motel tonight and maybe if he's lucky the bear's will get him before I do. Just kiddin! I am old enough to remember some of the dumb stuff I have done over the years.......and some of it wasn't all that long ago.
                      Anyway the super said things are going OK. The compressor problem is giving the guys a chance to practice the dying art of actually hand nailing.
                      Woussko, I gave him your suggestion of beating on the regulator. Said he would rather beat the kid who let the other compressor get stolen, however being an old hand he had tried rapping on the regulator box, to no avail. He decided to live with a 70% compressor rather than breaking it completely and having a no compressor.
                      Thanks for all the help.........Ray

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