Electronic – slow down a 3 speed motor

motor

I have a 3 speed single phase A/C motor inside an indoor air-con blower and it runs very noisy (not mechanical/installation issue but just the fan moving air is noisy itself) even on its LOW speed setting. Can anyone advise a way to slow the motor speed down to about 50% of its current speed. I'm not too worried about the MED and HIGH speed setting but if can just do for LOW speed setting would be great. (If slow for LOW, MED and HIGH together is also fine.)

I looked at VFD's but they all seem to be for 3-phase motors. Also someone suggested to join the HIGH and MED speed wires on the motor to the LOW speed and at the controller to put HIGH and MED to Ground.

Thanks in advance for any help. Picture attached.

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Best Answer

Reduce the voltage.

eg: connect it to 110V instead of to 220V

It's a fan motor it's designed to drive a speed-dependent load and run at reduced speed by slipping, reducing the supply voltage will increase the slip and reduce the speed without causing any damage.