Well pump short cycle

A few days ago I noticed that my well pump was short cycling. It would run for 15 seconds then stop for 30 seconds then run for 15 seconds, ect. until 50 psi was reached. I assumed that the air pressure in my tank needed to be adjusted because of the drastic drop in temperature this week. Tonight I shut off the breaker to the well pump and opened up a few faucets until the water pressure was 0. I checked the tank pressure and it was at 23psi, right where it has been for the last 7 years. The switch turn on pressure is 30 psi but if I set the tank to 28 (where it should be) the pump never kicks back on, I set the pressure at 23 and it has worked fine up until this week.
I removed the pressure switch and made sure the inlet pipe was clean and free of buildup (it was clean) I cleaned the contact on the switch and reinstalled it. On the side of the switch there is a lever with 3 positions AUTO, START, and OFF. I set the switch to start and the pump will only run for 15 seconds even though the contacts on the switch stay engaged. after about 30 seconds the pump will come on and run for another 15 seconds. this continues until the 50psi cut off pressure is reached.
Since the pressure switch is cheap I plan on replacing it as soon as Lowes opens up in the morning, I'm hoping that it fixes my problem but I'm doubtful. has anyone had a similar problem or have any suggestions?

Some back ground on my system.
Submersible pump (unsure of hp)
cistern (not well) water is clean and tank is more than halfway full
entire system is only 7 years old, same as the house.

Thanks in advance,
Bob

Maybe a thermal overload switch?

Quote:

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Originally Posted by jadnashua

Maybe a thermal overload switch?

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+1
If the pressure switch contacts are staying closed then the thermal overload is the likely suspect.

I replaced the switch today because the contacts were looking pretty bad anyway, no surprise I still have the same problem. I assume the thermal overload is on the pump itself?

I'm going to Ohm out the well pump wires, I'm hoping its the control box and not the pump though. Thanks for the replies.

Bob

All the wires checked out okay (no shorts) but when I opened up the control box I noticed that the capacitor was popped open on one end. I ran into town and got a new control box ($67) I swapped it out and now the pump runs smoother and quieter then I ever remember. It made it through the whole cycle without an issue so hopefully that was it.

Sounds like you resolved the immediate problem. Hopefully the pump didn't suffer too much from it. Given the average lifespan for one is about 7 years, you are now on borrowed time.

Really? Only 7 years for a pump. I thought they lasted much longer. It's a 1/2 gallon pump in a cistern so it's only pumping about 15' to the house.