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.
Issue with Blower Motor Not Spinning Up
blowerelectric motortroubleshooting
Related Solutions
The cooling test sequence for this board, says to jumper Y & G to R. Make sure the fan comes on, and spins up to the proper speed. Then remove the jumpers, and check the fan off delay.
If the blower does not come on, verify that the COOL terminal is energized. Use a voltmeter between COOL and neutral, and verify 120 volts (with jumpers in place).
If the COOL terminal is energized, check the motor and verify all speeds are working properly.
If the COOL terminal is not energized, the board my be bad.
According to the schematic you've provided, you have a multispeed blower (which is quite common). The speed at which the motor runs, is determined by which wire is energized. Energizing the red wire; for example, will run the motor at low speed. Energizing the black wire, runs the motor at high speed.
Before you disconnected the board, one of the motor wires was connected to the HEAT terminal on the board, and one was connected to the COOL terminal. Looking at the ladder diagram, it looks like the blue (MED) wire was connected to the HEAT terminal, and the black (HI) wire is connected to the COOL terminal.
If you've run the tests described above, and found that the COOL terminal is energized when the jumpers are in place. You can try connecting a different speed wire to the COOL terminal. If the motor spins up with the other wire connected, it means that the original speed is dead or something's wrong between the board and the motor.
It looks like the LO speed red wire is attached to the M1 terminal on the board. I'd swap that to the COOL terminal (just temporarily for the test), and see if the motor spins up when the jumpers are in place.
WARNING: DO NOT run the A/C for long with the motor at a lower speed..
Sounds like the capacitor in the AC blower motor is failing.
The electrolytic material dries out over time, leaving the motor unable to spin.
Replace capacitor with one of the same rating.
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Best Answer
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":
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...