Selonoid staying open?

Hello all you electrical geniuses!! What could cause a selonoid to stay in the open position? Earlier my compressors kicked on at 110psi like they should, but when they hit 150 they kept on going instead of shutting off. I checked the pressure switch and it is working properly. They seloniod activation wire was not powered at the time. I ended up pulling my main fuse to shut the system down. All this happened on my way to work and only had a few minutes to trouble shoot.

I have everything grounded to the frame. Could a bad ground be the cause of selonoids sticking open?

Any advice is appreciated, this whole system is less than 3 weeks old so im still working the bugs out

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I would say that its bad because if not hooked up properly or not grounded then the compressor wouldn’t kick on (someone correct me if i am wrong)and I would also suggest putting in a cut off switch in the cab.

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When you say solenoid, are you talking about the relay for the compressor?

What pressure switch do you have and how did you test it?

Yes, selonoid = relay… Sorry bout that

To test i used a cheap test light. The pressure switch is a HB 110-150 psi. I put the test light between the pressure switch and relays. At 150 the test light shut off, which means that the pressure switch is working correctly (at least i think so). At this point though the relays dont “close” and shut down the compressor. Ill break out the multimeter tomorrow and tear into it i guess.

Here is a pic of what relays im using. They are both brand new, i had them laying around from a different project i never got around to. I think they are rated at either 40 or 50 continous amps and yes they are 12 volt. Not 6 or 24.

1 relay per compressor

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Wowzers… There’s gotta be a better way to do that.

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So the relays are stuck open permanently (i.e. fused closed)?
Got any specs on the relays you’re using? I’m assuming / hoping they’re not starter or latching relays.

I don’t like how you’ve got the coils on the solenoids wired in series, but that aside since it shouldn’t be the cause of your problem. Let me know on the above first and I’ll get back to you.

The coils being wired in series, what problems would that create? I can give them each their own wire, it wouldn’t be a problem. The relays are continuous duty, I originally bought them for a golfcart but like mentioned above they never got used on that project. As of right now they are open permanently, I am hoping they aren’t fused, heading outside shortly to see what I can find…

Yeah, every relay has a solenoid and I forgot you had the bigger solenoid style…

Anyway, no need for a multimeter. Sounds like a good test with the test light.

To me, all the wiring looks good except I question one thing. The triggers come in and parallel between the 2 solenoids. But it looks like you have the grounds connected to the mounting feet? Shouldn’t the grounds be connected to the posts next to the trigger posts?

BTW - if a circuit is stuck on, it is closed.

When you open a circuit, you break a contact, which is off.

They are self grounding, but since I mounted them on plywood I had to run ground wires. Not sure what the other post is for, I bench tested these and couldn’t get it to do anything using the 4th post…

So you can ground them anywhere on their body… Then the 2 posts have to be for something.

To DBO’s point, they could be latching relays. Meaning it takes a 12V trigger to connect and latch the relay. It stays latched even if power is removed. Then it also takes a different 12V trigger on another post to open the relay.

You could try putting 12V to the open post real quick.

Constant duty isolation relays like that will need a specific voltage across the coil to close the contacts. Wiring them in series like that will drop the voltage and could cause them not to energize at all, or cause the internal main contacts to chatter and spark. Arcing across the contacts can cause issues but for both to fuse into the closed position would be very very unusual. Regardless, you should have them wired in parallel. The two pins by the way should be for the coil. One going to ground and the other to energize the coil.

Did you ever actually hear them click (i.e. throw closed)?

As already said, it’s very strange that both relays are closed permanently unless they’re latching relays or an NC (normally closed) type. See if you can find any kind of marking (i.e. serial or make) on the relays so we can see exactly what specs these have.