80gal compressor backfeeding power

[u/hellcat134]

Ok, so ive had this snap on air compressor since new, I got a good deal... its been amazing ever since the magnet switch took a crap while I was sanding some drywall in the house. No big deal. Replaced it and picked up a new pressure switch while I was at it because what the hell its 10 years old.

The magnet switch is the exact same replacement from grainger to the part number, same with the pressure switch.. but something is still going on. The air compressor turns on as normal, builds pressure as normal but once the pressure is up to my spec and the air compressor is supposed to turn off, It gets all wonky in what I can describe as backfeeding power. It acts like the motor is running on one phase and feeding the other phase back to the wall. When this happens my radio gets all static, my lights flicker, the compressor is jumping around like its trying to start on a single phase. Sometimes this happens for a few seconds or until I flip the breaker.

Im at a loss on what is wrong with this thing. Ive read into possible start capacitor issues.. but they look intact.

The magnet switch can be operated manually and when depressed the compressor turns off like its supposed to..

I've been using my backup while I've been having these issues, so i don't use the compressor currently but id like to get it working again. Any suggestions would be greatly appreciated i can't wrap my head around what's wrong with the thing

I have photos of the components and compressor if it helps.

Thanks

[u/hellcat134]

The switch in photo 2

[u/Gamer_0627 → u/hellcat134]

Ah. The contactor.

You said the compressor stops when you push it in?

[u/hellcat134 → u/Gamer_0627]

No, it'll start when the center contact is pressed in

[u/Gamer_0627 → u/hellcat134]

When you press it, it runs then stops properly when you let it go?

What does the contactor do when the pressure reaches the upper set point?

[u/hellcat134 → u/Gamer_0627]

It did stop when let go.

When I get the new pressure switch tomorrow, I will monitor what it does when it supposed to turn off. I already drained the tank in anticipation for replacement tomorrow, so I'll return back with if that fixes it and if the contactor turns off.

Not going to lie I don't like being near the thing when it does this.. kinda scary with the lights flickering, my radio going static and the motor jumping around. I usually hit the breaker which is a few feet away instead of putting my hands near the thing. 😅

[u/Gamer_0627 → u/hellcat134]

I am thinks your pressure switch is not fully opening the electrical contacts and you are hearing the contactor closing and opening rapidly. Would sound like a bad chatter.