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New Pressure Switch question

Discussion in 'Compressors' started by Melzy, Jan 14, 2022.


  1. Melzy

    Melzy Young Tutorling

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    Hi peeps,
    My AirCom 20A compressor wouldn't auto switch off, then it released air and kept running until releasing air again. I quickly turned it off. Research indicated my Pressure Switch on my 10 year old oil filled compressor needed replacing. Replacement also didn't work in the same way and I have sent it back and ordered another one today.

    My question is: Do I need to set the cut off pressure setting on the new pressure switch?

    My compressor has a max. pressure of 6 bars. The original pressure switch was set to cut off at 6 bars and cut back in at 4 bars. I noticed on my returned switch that it had mentioned being factory set for 5 - 8 bars. Does that mean it would cut off at 8 bars and cut in at 5 bars? My compressor can't reach 8 bars so would I have to turn the screw in the pressure switch to lower the pressure setting to 6 bars? And if so, how would I do that properly?

    Or am I just simply misunderstanding things and the new pressure switch should just work right out of the box. I don't want to keep returning Pressure Switches because they don't work and it might be something I am doing wrong. Any insight would be truely appreciated.
    Cheers Mel
  2. jord001

    jord001 Air-Valve Autobot!

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    Hey Mel, Mine was set for 8 bar off and 6 bar back on when I had a replacement but that's ok for my garage compressor. Yep you will need to adjust the screw inside to change the pressure to 6 and 4 if its set at the higher setting.
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  3. Melzy

    Melzy Young Tutorling

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    Thanks jord001, the trouble is that the videos I have watched show people let the pressure build to the cut off pressure and stop, turn off power at the mains then do the rest. They have much bigger compressors than my Aircom 20A. My compressor has a max pressure of 6 bars so won't be able to reach the factory setting of 8 bars on the new Pressure Switch. I don't know if I turn the screw before starting the compressor will work to lower the cut off pressure. Do you or anyone else know?
  4. jord001

    jord001 Air-Valve Autobot!

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    Yes if you turn it first it will only go up to what ever you set it at. Now I'm unsure if you tighten or loosen the screw to make it shut off earlier. I would have thought loosen to make the spring softer but don't quote me on that. Also there might be a + and - on the switch plate somewhere which will help

    EXPERTS please chime in now :)
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  5. Melzy

    Melzy Young Tutorling

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    OK great, I'll do that when the new switch arrives on Wednesday if it doesn't auto turn off at 6 bars. Yes according to what I've learnt - is lowering pressure and + is increasing it and it is marked inside the switch. I will go slow and do quarter minus turns and keep my fingers crossed. If that doesn't work it could be the Check Valve and I have found a similar one I can order. If that fails I will stick with my AS186 and Mini cordless compressors :laugh:lol
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  6. Melzy

    Melzy Young Tutorling

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    OK the next new pressure switch arrived yesterday and looks alot more like my old one which is reassuring. It had information on the box which told me it was factory set to 8 - 6 bar cut off/on which the other box didn't. I fitted it lastnight which but discovered it leaked at the pressure release valve (PRV) and built no pressure at all.

    The next day I disconnected the hose from the PRV and tested the switch again with my thumb over the end of the hose. It built pressure which proved that it had a faulty Check Valve. I could adjust the pressure cut off/on with my thumb trick and I'm happy to say that turning the screw inside the pressure switch to minus in 1/2 turns eventuall brought it down to the desired 6 - 4 bar cut off/on. Hooray!! If you ever do this always unplug the power before removing the Pressure Switch cover :thumbsup:

    I have now ordered a new Check Valve which should arrive by Saturday. Fingers crossed that fixes my compressor for another several years :)
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  7. Melzy

    Melzy Young Tutorling

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    Update: The new Check Valve arrived on Friday and I fitted it onto my compressor with no problems thanks to the advice I got from Airbrush Services Almere where I ordered it. Unfortunately I am still getting a leak at the Pressure Relief Valve behind the Pressure Switch (it comes as part of the switch).

    Happily I disconnected the tube attached to the PRV and did the thumb over the end of the tube trick. I started the compressor which could now build pressure because my thumbs blocking the leak. It cut off as it should at 6 bars AND when I took my thumb away it held the air in the tank. This means both the new parts are working correctly! :)

    However it still leaks from the tube when attached to the PRV :( probably because I haven't fitted the compression ring (Olive ring) properly. I am now waiting for some new Olive rings to arrive from the UK as I can't find where to buy 5mm Olive rings in Holland. Once they arrive ( I bought spares) and I manage to get a good seal, I'm hoping to finally have my compressor up and running again. Fingers crossed folks
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  8. Melzy

    Melzy Young Tutorling

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    I'm still waiting for the Olive/compression rings to arrive from the UK, it's 2 weeks!! Rediculous!! It used to be 3 days to a week maximum. Trying to be patient but its getting low.
  9. JackEb

    JackEb The Dragon Hunter Staff Member Admin

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    transport is messed up globally, even down here in Australia things that use to take a week are now 2-3 weeks
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  10. Melzy

    Melzy Young Tutorling

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    Yeah it really sucks JackEb
  11. Melzy

    Melzy Young Tutorling

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    Hey Everyone! I am totally happy and thrilled to tell you I fixed my 20A compressor today!!! Yeay, mega happy dance going on :laugh:lol

    My new Olive rings still hadn't arrived this week so it occured to me to try switching over the new Pressure Relief Valve that sits behind the Pressure Switch, with my old better quality one. Guess what? It worked!!! Even with the well squashed existing Olive ring!

    I am over the moon folks because I'm a night person and live in a second floor poorly insulated Amsterdam flat so I need the super quiet, fridge level noise compressor to paint when my neighbours are in bed. Now I can actually start painting again although I need to practise loads :):laugh:
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  12. JackEb

    JackEb The Dragon Hunter Staff Member Admin

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    woohoo, happy dance indeed.
    Glad you finally got a result, it can be frustrating trying to fault find
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  13. Melzy

    Melzy Young Tutorling

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    Thanks JackEb, it was frustrating and I started dreaming of buying a new one but happily I finally fixed it and thats a great feeling. Gave it a total oil change too :):thumbsup:
  14. JackEb

    JackEb The Dragon Hunter Staff Member Admin

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    haha, I run oilless for my airbrush, but you've reminded me that the big boy in the shed could probably benefit from an oil change.
  15. AndreZA

    AndreZA Love this place! Forum Supporter Very Likeable!

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    *have to get mind out of the gutter*
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  16. JackEb

    JackEb The Dragon Hunter Staff Member Admin

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    I didn’t think you had a spot in our gutter Andre ! You’re normally the sensible one here :D
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  17. Melzy

    Melzy Young Tutorling

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    lol:laugh:
  18. AndreZA

    AndreZA Love this place! Forum Supporter Very Likeable!

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    I blame Covid . :malicious:
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