Can I put a fan control switch on a window air conditioner to quiet it down

Question

Can I use something like this to control a window air conditioner so it will run quieter?

Variable Speed Fan Control, Wall Mount, Rated 15.0 Amps @ 120 VAC for use with Shaded Pole and PSC Motors

Answer 1

Assuming the motor for the AC fan is of the proper type, "shaded pole" or "PSC", then yes, if you opened up the unit and tapped-in to the fan control circuit itself. This device would not work if you tried to power the entire AC unit from it.

I suspect, however, that the motor is neither of the above types. Further, you are looking at significant safety risks by modifying a self-contained AC unit in this way. It would certainly void any manufacturer warranty and may also create a safety hazard.

Most window AC units I've seen have a built in speed control. Is there some reason why you can't just use what is designed into the unit?

Answer 2

Slowing down the fan in a self contained air conditioner will change its ability to operate as designed. It is not possible to predict how much the unit behavior will be changed since every unit has its own design parameters. However you should consider the case where you stop the fan completely or have it running at a very low speed and you can see that the ability to cool the coils will stop.

I highly suspect that even with a small change in fan speed most units will increase the overall energy usage to achieve the same amount of cooling capacity.