Fix the electric motor on my air purifier

Thanks for the inputs. I updated my post with the images. This is a Hunter Tower Air Purifier (HP670).

@ztwrhk3g6luccw6

Might be just shadows in the 1st image but the 2 capacitors near the green R1 resistor and the yellow component look like they got hot as there seems to be black scorch marks at their base.

If you turn over the board, you can see where the H M L connectors go to on the board by following the tracks that they're soldered to. H M L = high, medium low

@jayeff Thanks - I uploaded additional pictures of the circuit board. It appears it was just shadows. The capacitors, and other components visually look fine. I don't see any issues with them.

I wonder can I test these components with a multimeter?

@ztwrhk3g6luccw6

If your DMM has a capacitance test you can but they need to be disconnected/removed from the circuit board first.

You can also test them using the Ohmmeter function of a DMM as well but it is not so accurate.

Once they're removed formth eboard set the Ohmmeter to measure the highest resistance e.g. 20MOhms and then connect the meter to the capacitor legs.

The meter should show a moving resistance value which slows down.

This is the meter charging the capacitor. Once the meter has stopped or slowed to a crawl, revers the meter lead connections on the capacitor and it should discharge through the meter as shown on the meter.

If you measure short circuit i.e. 0.00 Ohms (try lowest resistance scale to confirm) or infinite Ohms (OL on meter perhaps) i.e. open circuit then the capacitor is faulty.

Be aware when remove the capacitor from the board as they appear to be the electrolytic type i.e. polarity dependent.

Take note of the markings on the can the -ve leg has a stripe down the side of can

@ztwrhk3g6luccw6

You could also test if the speed switch is OK by checking if there's a circuit between the H, M & L wires on the board and say and earth when the appropriate switch setting is selected e.g. press the low speed setting and check if there is a connection between the L and earth etc.

Not sure if there will be one as there's no schematic but you have to prove the the switch works as well as it determines which capacitor may be connected to the motor to affect the speed, or if not a capacitor the voltage etc.