Ah, yes. This is a point I really should have made.
If you've been "bit" by a small cap on a circuit board, imagine one as big as an adult's fist. I don't recall the output of this thing but one needn't read the label to know that if I can't completely enclose this thing in my hands, it's probably not something one should...enclose in ones hands? It is also in a nice metal container that's probably under more pressure than it should be; mine were always bulging.
With board mounted caps, a lot of this stuff lands in the "leaving pizza out overnight" category. I've only had one (small one) truly explode[0] due to age/being defective; several that I blew up in electronics class when the teacher's head was turned, but hey. And about a flobbidy-gillion that bulge, you could lick the leads (that's sarcasm, don't actually do this).
Now, fan caps/mostors like this -- I've been bit by (a 400V cap that was "not dead yet") -- I don't know that I actually touched the leads so much as some hair on my exposed arm made contact (it's why I wear my long welding gloves!). ...There's that moment well after you've registered the burning sensation and smelled the hair that you say a prayer of thanks to God while panicking that the business end is not yet any safer than it was a second ago.
The (somewhat unsafe) procedure I used was: Cut the power, pop the fuses, pulled the wires in the order I had in my notes from last time (with thick welding gloves[0]), pre-cut electrical tape to cover the three leads (model has lots of distance, it's a big cap). The cap is connected by three wires, far from the rest of the electronics, easy to get to, easy to remove/re-secure the wiring, admittedly -- easy to get a little too comfortable.
Carefully handle those leads; hopefully goes without saying -- even if the cap isn't bulging -- avoid heat-based treatments (hot glues/heat shrink). I tape the hell out of the big ones. I've only had to personally handle a small number of these, but there's a TV repair shop in the area that does free electronics recycling. I told the puzzled 15 year old at the counter what it was, he looked puzzled, so I explained that it can explode like a hover-board battery and he shrugged. I guess...good enough.
[0] In a manner that might have been a fire hazard, and were it exposed, could have taken an eye out. In my case, a moderate "pop", a black spot on the board, smoke, and shrapnel throughout the small case.
Just to disclaim a little more -- I definitely would do this at home, and the first time I did something like this was before I started doing any real circuit work at home.
I take into account the typical audience of the site, though. Most of us tinker/work with highly complex things that require good research skills even if they don't touch electronics. The basics of how a fan capacitor works, how to handle one safely -- including testing, and discharging, can be done for less than $100 in parts including the required resistor/multi-meter -- in my case. But after inspection and planning, I opted for skipping some precautions and relying on "being careful"[0] which I don't recommend, but how many deaths is that, really, if we all try it? (/sarcasm)
In the case of my unit, there was maybe three seconds where -- if a reasonable enough charge were present (and I had every reason to believe it held enough to hurt ... a lot ... which is motivation enough) -- I was in danger of receiving it if started pouring on me spontaneously on a clear day -- I didn't have remove the cap from the unit to secure the leads. I suspect a lot of A/C units are similar, but YMMV and I'd be willing to bet, again, most readers of this site possess the wisdom to judge the danger for themselves after suitable reading/watching.
[0] Common sense which starts with Rule #1: Always have a physical witness if you're working on something that can kill you and ends with #2: Use them to double-check your research if it isn't obvious stuff (or my personal favorite, have them handle the dangerous stuff).
If you've been "bit" by a small cap on a circuit board, imagine one as big as an adult's fist. I don't recall the output of this thing but one needn't read the label to know that if I can't completely enclose this thing in my hands, it's probably not something one should...enclose in ones hands? It is also in a nice metal container that's probably under more pressure than it should be; mine were always bulging.
With board mounted caps, a lot of this stuff lands in the "leaving pizza out overnight" category. I've only had one (small one) truly explode[0] due to age/being defective; several that I blew up in electronics class when the teacher's head was turned, but hey. And about a flobbidy-gillion that bulge, you could lick the leads (that's sarcasm, don't actually do this).
Now, fan caps/mostors like this -- I've been bit by (a 400V cap that was "not dead yet") -- I don't know that I actually touched the leads so much as some hair on my exposed arm made contact (it's why I wear my long welding gloves!). ...There's that moment well after you've registered the burning sensation and smelled the hair that you say a prayer of thanks to God while panicking that the business end is not yet any safer than it was a second ago.
The (somewhat unsafe) procedure I used was: Cut the power, pop the fuses, pulled the wires in the order I had in my notes from last time (with thick welding gloves[0]), pre-cut electrical tape to cover the three leads (model has lots of distance, it's a big cap). The cap is connected by three wires, far from the rest of the electronics, easy to get to, easy to remove/re-secure the wiring, admittedly -- easy to get a little too comfortable.
Carefully handle those leads; hopefully goes without saying -- even if the cap isn't bulging -- avoid heat-based treatments (hot glues/heat shrink). I tape the hell out of the big ones. I've only had to personally handle a small number of these, but there's a TV repair shop in the area that does free electronics recycling. I told the puzzled 15 year old at the counter what it was, he looked puzzled, so I explained that it can explode like a hover-board battery and he shrugged. I guess...good enough.
[0] In a manner that might have been a fire hazard, and were it exposed, could have taken an eye out. In my case, a moderate "pop", a black spot on the board, smoke, and shrapnel throughout the small case.