On 3 Aug 2006 04:00:15 GMT, firstname.lastname@example.org (DoN. Nichols) wrote:
Funny, most 3 phase units I've seen have high starting torque.
Some units have shutoff solenoids, and start under headpresure,
even after long off-periods.
But since this is crossposted to alt.home.repair, I can see why the
presumption is made, since you likely only deal with residential
Well ... I've observed a failure from a power glitch in an
industrial unit (out where I worked before I retired). I was sitting
out in my car relaxing at lunchtime, and I heard a loud whooshing sound,
and saw a dense white cloud billowing out of the room which had the air
conditioner compressors, along with other HVAC stuff for the building.
It turns out that it blew a hole in the compressor's crankcase.
It apparently tried to start with liquid in at least one cylinder, and
the three phase motor *did* have plenty of starting torque -- too much
in terms of the health of the multi-cylinder compressor.
Luckly, there were two other units in the same room which did
survive, so we were not baked out of the building until repairs could be
Well ... I'm the one you quoted, and I was posting from
rec.crafts.metalworking instead. Still not as an expert on
refrigeration systems, but with a bit of mechanical knowledge at least.
And -- if this system had had an electronic time delay on the
restart as my home system does, it would have survived, and would not
dumped a large quantity of whatever refrigerant it happened to use.
This was before the changing regulations forced us to abandon the Halon
(another CFC) fire control system in our large computer room and replace
it with dry-pipe water fire extinguishers.
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Common terminal. The can is (unless defective) isolated.
One of your terminals may be shorted to the (grounded) can, thus causing
your circuit breaker overload.
Costs about $10 or $20 at http://www.grainger.com/ to get a replacement.
Also all over eBay.
If there is a short in the cap, that's one place there won't be any
visible sparking and maybe nothing visible.
It says what it is on the can. If not, I guess a diagram, and if not,
maybe the AC supply house knows. If you know the value you want you
might get it cheaper at an electronics supply house, but they might
not even sell one that big. Never tried.
I doubt it.
If it's the cap, you may have gotten off cheap. Good for you.
This is symptomatic of a bad compressor. Try testing the motor leads for a
dead short (to each other and ground). There are start and run leads. You
may need a HVAC guy to replace your compressor and recharge the system.
Um, no, that could not be the case. If I disconnect the cap's fat blue
lead and let the cap hang in the air, the breaker does not blow, the
blower runs, and the compressor hums (I am sure that it does not run).
It is very likely the cap.
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