I have a Dayton Blower motor. Model 3K617K. It has a clutch that is supposed to engage when it spins up. However mine never gets up to speed. It turns, but slowly and constantly makes the loud humming/chugging noise it would normally make just for a few moments before the clutch engages. It does this with no load on the motor. If I lease it running for any amount of time it either gets considerably hot, or trips the 20 AMP breaker. I have taken it apart and verified that the clutch is free to move. Given all the above I'm afraid it's an issue with the windings meaning I'll need to replace the whole thing. Is there anything else I should try or check.

2 Answers 2


OK, so that is a "Split Phase" AC induction motor, meaning there is a centrifugally operated switch inside of it that is supposed to change state at a certain speed in order to allow the motor to run. Without getting too deep in the weeds of AC motor theory, single phase motors will not rotate on their own, they need to be "tricked" into starting to rotate, then once they are, they will continue doing so. One of the "tricks" is called a "Split Phase" design. The winding is in two parts, one of them designed to"bump" the motor in one direction, the other designed to run it once it begins rotating. The first part has low power capability, all it is supposed to do it get it started (bump it), then a centrifugally operated switch on the shaft kicks in the other part of the winding that actually creates the rated torque. That centrifugal switch is not functioning correctly in your motor, so it appears as though your start winding is being left in place and the run winding is not being connected.

These switches wear out, or they get filled with dust and gunk over the years, especially if the blower is being used for dust collection or extraction, like in a cooking vent hood. In most cases, that switch is located under the end bell housing on the NON drive-end of the motor, meaning the end WITHOUT the shaft that is connected to your clutch. The simplest attempt for you to try is to open that up and spray in a bunch of "Electrical Contact Cleaner" that you can buy from most hardware or auto-parts stores. Just do NOT spray it in there with the motor plugged in, and let it thoroughly dry out before you do apply power; that cleaner is flammable.

In this photo, the centrifugal switch is not labeled, but is directly below the word "winding": enter image description here

If that doesn't work, the contact points are likely burned and it needs to be replaced, you can buy replacement centrifugal switches over the internet from numerous sources, probably even Grainger (who sells the Dayton line). That's not a job for the feint of heart however, there are springs and levers and wires that must be carefully disassembled and reassembled. So if you DON'T want to tackle that, you can remove the motor and take it to a motor shop, they can do that for you. Or, you can just buy a new motor, it might cost you less...

  • Thanks for the really detailed answer. I get what you are saying about starting a motor with a single phase. I have a static phase converter that I use to run a 3 phase motor, but I didn't realize this also applied to motors designed to run on single phase. I will definitely go back and check the switching mechanism better. However I'm not sure if it is a problem with the contact. From what I can see, the contact is normally closed. It opens only when the centrifugal device engages. It seems like it's not getting enough speed to actually engage it. Or maybe there is a mechanical issue? Mar 10, 2018 at 1:36

What device is this motor for? It is a multi-voltage motor, so, Are you sure that it is wired correctly? That clutch you are referring to is not a clutch but is probably the centrifugal switch to remove the start winding from the circuit. The fact that it get hot is an indication that the wiring is not correct. You should edit the wording of some of the sentences so they make sense. It is very hard to understand what problems you are having. My best guess is improper wiring.

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