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Discussion Starter · #1 ·
Air Compressor problem. Tank pressure activates pressure switch activates magnetic starter activates electric motor.

Air pressure "Unloader" copper pipe goes from tank to pressure switch to turn compressor on. Air pressure from tank goes to pressure switch to turn compressor off. This is a spring loaded setup where one of the previously mentioned systems pushes the two connections away and the other system pushes them together all in one mechanical assembly. When the two connections connect that is when the starter is activated.

Think of it as giving someone high five with both your hands at the same time with enough clearance to put one or two credit cards between each others hand.

Problem happens when the compressor is about to reach cut in or cut off. When the connections are about to connect they start to touch each other and separate quickly causing the starter to activate on and of repeatedly. Like when you flicker the light-switch. There is very little clearance between the connections and they appear to be magnetic. Because of the bad design of the pressure switch the sparks start to fly from the magnetic starter, and the starter makes loud knocking noises and sometimes trips the breaker, and it causes the motor to turn on/off repeatedly which can't be good for it.

Once it connects or disconnects then it is fine. The problem is the transition from on to off and off to on. It seems to be because of the incremental movement and because of the microscopic clearance between the two connections.

Is this normal? Does the pressure switch need to be fondeled with? Do I need a different size spring? Do I need to find a way to create more clearance between the connections?

Campbell Hausfeld CE7000
New, never ran correctly
Factory installed starter
Electrician installed plug
7.5 HP 80 gallon 175psi
 

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What are your max and min pressures set at? If they're both at the same pressure, it won't work. Adjust them to 100 and 140PSI (or whatever your manual says they should be at). Unless I'm mis-reading your question?
 

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I pretwist and then use wire nuts. Solder pots rule.
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A pressure switch on a compressor should be a descent quality. I like the square d ones and make sure it has the unloading valve. They seem to last. If yours is chattering then replace it and make sure you set the differential enough to keep it from cycling. Don't reuse the unloading valve, a little oil in it and it sticks like crazy.
When your done, time it's natural on/off cycle a d write it inside the starter. Then you will see over time how bad the compressor is aging and if there are new leaks in the system.
 

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A pressure switch on a compressor should be a descent quality. I like the square d ones and make sure it has the unloading valve. They seem to last. If yours is chattering then replace it and make sure you set the differential enough to keep it from cycling. Don't reuse the unloading valve, a little oil in it and it sticks like crazy.
When your done, time it's natural on/off cycle a d write it inside the starter. Then you will see over time how bad the compressor is aging and if there are new leaks in the system.
He mentioned it was new, so I'd guess someone at home depot fooled with the settings.
 

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I pretwist and then use wire nuts. Solder pots rule.
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SteveO. said:
He mentioned it was new, so I'd guess someone at home depot fooled with the settings.
Could be, but he's a DIY type so it don't matter.
He wouldn't understand anyway.
 

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Bilge Rat
motors and controls.........
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If the motor runs at 3450 RPM, then it's a dead giveaway that the compressor was built using the cheapest parts available.

If so, my bet is on a chintzy pressure switch that will never work properly.

As noted, get a Square D switch. And not the cheapest one they have.
 

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Discussion Starter · #7 ·
What are your max and min pressures set at? If they're both at the same pressure, it won't work. Adjust them to 100 and 140PSI (or whatever your manual says they should be at). Unless I'm mis-reading your question?
i can adjust it to whatever i want it to be. right now it is at about cut in 145- cut off 175 which is factory recommended anyways.

seems to be a bad pressure switch out of the box. came installed on the compressor.

was looking for confirmation, if anybody has seen this before, and knows what this symptom means.

to simplify it if you have a knowledge of how it works...When it is supposed to cut in and cut off...it does not do it smoothly from (on to off when cutting off) and from (off to on when cutting in)...it should transition instantly as it reaches the min and the max(like all my old compressors). Instead as it comes close to the min/max it rapidly switches off and on about 5 times, instead of just once. This causes the starter to knock, and sparks to fly from the starter, and the electric motor to jump on and off violently, and sometimes the breaker pops out on top of all that.

I can see it is happening because the connection and separation of the wires by the pressure switch is affected incrementally by every single psi lost and gained, causing it to connect and disconnect itself when in the process of separating or connecting. Let's say at point A the wires are 100% connected and at point B the wires are 100% disconnected. The problem occurs while it is traveling from point A to point B and from point B to point A. It doesn't jump from A to B, it actually travels through everything in between and it could stop in that position forever if you wanted to leave the psi as it is in that moment. That is when it goes on and off 5 times until it reaches the other point (as the psi keeps increasing or decreasing to get the pressure switch there), where it is securely off or on.
Even then the gap is only thick enough for a credit card to slide through.

looking at the crappy design of the pressure switch I don't see how this could ever work properly even if I got a new one, but then why would they put this same switch on thousands of their compressors if the design was as crappy as I think it is. this can't be how it is supposed to work, right?

Gonna call Campbell Hausfeld for service or a new pressure switch since it is a new $2000 compressor. I will use my old compressor in the meantime to prevent damage to the motor. If Campbell Hausfeld fails me then I will have to buy a different pressure switch from Condor USA, because I have seen that one work properly for years on my old compressor.

http://www.grainger.com/Grainger/CONDOR-USA-INC-Pressure-Switch-3FWC4?Pid=search
 

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