Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: why does this machine start to make a crackling sound?
Document: I then slept for hours comfortably.The con: It makes a small snapping sound when it needs to be cleaned. I use that as a reminder. It doesn't constantly make the sound. I will from time to time, then more often as it gets dirtier. It is hardly noticable to me.As for the charcoal filter. You don't need to have it. It is a plus. I haven't gotten a refill since I got my machine a long time ago. I am thinking about getting it though.
This is my second time buying this product as I got one for my daughter's room and it worked so well that I bought one for me. The only issue is the zapping sound every now and then when dust is being cleared but it is infrequent. The silance mode is really queit but you can still hear the machine.
One person complained about the "popping and snapping" noise it makes.Yes, the Oreck purifier will make this annoying sound if something large (like a fly or moth) gets sucked into the unit.To fix this problem, I simply vacuum the bug-out.Another reason for the "popping or snapping" noise is: If you wash the filter, and it is not completely dry, it will make this noise.You have two options to fix this problem.#1.
Then it's out of commission for a day while it dries. There is a lot of dust collected and the color of the water when you soak it is kinda dirty, so I guess it's working. I like it as a white noise machine, but lately it's making a really strange buzzing sound like a weedwhacker, so that I can't even use it anymore, because it literally wakes me up in the middle of the night, even with earplugs in.
And it is extremely loud! Enough to wake you up or overpower a movie with surround sound.This is an extremely flawed product that should have never been on the market. I'm surprised that an authority on business practices hasn't looked into this.When I saw a few of the good reviews, I had to speak up. I'm not going to allow sockpuppets mislead other people.
I recommend it. In fact, I have Honeywell version attached to my furnace for whole-house cleaning and it works the same way, cleans the same way and I no longer have to buy furnace filters.Nice thing about this technology is that it is capable of precipitating out smells as well as the smallest particulates. Paper filters just start to stink.
Let me start by saying I literally just returned this exact model today back to Costco. They are having a sale right now where you get $50 off and you end up paying $148 a piece, in the store you need the coupon but online it just defaults to the $148. I took advantage of this on Friday (runs till like 15 Apr) as I have always considered buying one and when I saw it in the store I could not resist.
A dirty cell lets the dirty air pass through it with little filtration. (3) Cell must be "completely dried" after cleaning, for 6 to 24 hours, depending on humidity, otherwise the air purifier will not start. (4) Cell captures a higher percentage of particles at lowest fan speed than at high speed. (5) Percentage of particles captured by Cell varies from 0% to 80% depending on how clean the Truman cell is.
Four years ago, I suddenly developed allergies. The allergies caused severe breathing problems (I couldn't draw a full deep breath without effort) and because of the allergies, I also has chest pains whenever the breathing issues started. While I did start daily medication, I found that the symptoms frequently overrode the medicine. My allergist recommended an air purifier for my home. A friend recommended Oreck, and I went to a local Oreck store for my purchase.
didn't seem to make a difference in air quality...still sneezing...still coughing...it does get dirty, so it works.just doesn't seem to help with allergies...
Answer: That's because there are some large dust particles that OCCASIONALLY pass through it that come in contact with the electrostatic plate, and it makes a sound similar to the sound an outdoor bug-zapper makes- louder than usual cracking or popping noise for a brief second.