It’s kind of a cheap oven and about 12 years old. When I put some chicken mole in it a little while ago to heat up, it made a big *crack *sound, and then as it ran for two minutes, there was a series of smaller crackling sounds, sort of like crackling paper. The food heated up fine. Nothing burst into flames or anything,
Usually you get that sound, when there is metal inside. The crackling sound your hearing, may be electricity arcing. Was there an odd smell, ozone is kind of distinctive. So , yeah, my advice would be to send it to recycling and get a new one with annoying beeps.
The standard test is to put a cup of water in it (use a Pyrex cup) and turn it on high for 1-2 minutes. If it makes the noise during that cycle, get rid of it.
Secondly, at 12-years-old, I would say that perhaps it’s time for a new microwave. However, the crackling could have just been the food popping. That does happen and it’s nothing to worry about.
I get the same sounds from my microwave occasionally. It is well over 9 years old (it has been in my possession for at least 9 years; prior to that a friend used it in her office at work and she let me take it home when my previous one died). No obvious reason (I never put metal in, no dishes with metal trim, etc.) and it has no turntable. I have no idea why and was curious to see what answers you’d get. In my case I’ll just use it until it dies a painful death and then decide what to get to replace it.
Along the same lines as what jz78817 said, there are some foods that when microwaved, always make that kind of noise for me. Chicken in any type of sauce is the main one.
Another microwave question: I accidentally ran my microwave last summer without putting food in it, and it burned a quarter size hole in the inside top. The microwave still works, though my wife and I are hesitant about using it. Any real danger from running the thing now?
It’s possible that this will lead to Something Bad. The first rule of safety is to assume that all the other Bad Things that will lead to an accident have happened and you’re just one step away from kaboom. So, assume the hole in the top is that one thing and that the other bad things have or will soon happen. The solution is obvious: chuck it. (Not Goodwill or anything.)
As to the OP: Sometimes crud buildup causes this. Thoroughly clean the inside of the microwave and try it. But you can’t really clean the inside of the “horn” that feeds the microwaves into the box. Crud built up there is a major reason for shortened microwave lifetime. (And can be greatly reduced by covering things.)
Actually, in some states, thrift stores will take old in electronic items for free for the purpose of making sure they’re recycled and not tossed into landfills and other areas, such as illegal dump sites. My state, Washington, is one of them. I doubt the smaller mom-and-pop thrift stores do this but check with Goodwill and the other larger chains in your area to see if they’ll take your nearly dead microwave off your hands.