Running a portable air conditioner without venting it
If you're using it just for the noise to help your wife sleep, an improvement might be to record the noise the machine makes (such as with the sound recorder in a computer or phone), copy the recording to a CD with a computer, and then play it on a stereo in the bedroom when she's trying to get to sleep. That assumes she needs the noise only to fall asleep, but stays asleep without it.

Another possible solution is a white noise phone app, and a phone in a charger on a bedside table. This may also be useful for travel.

The reason to use one of those solutions is that they draw a lot less power than an air conditioner, and don't put unnecessary wear on a mechanical device with lots of moving parts.

Obviously, if you want the heating or air conditioning too, the machine makes sense, but if you just need the noise, then a device that specializes in sound is probably a better solution.