On Oct 27, 5:10*pm, "Doug McLaren" dougmc
wrote:
In article ,

jamesgangnc wrote:

| It is probably not the fan. *It's probably the compressor. *I'm
| thinking you can't replace the compressor because you probably do not
| have a recovery system and an oxy/acetylene set to braze the new one
| in. *But you could surprise me I suppose.

I will not be attempting to replace the compressor myself. *The
outside fan, that's easy to get to and I'd try it myself. *If it is
the compressor, I'll pay a professional for that.

But in this case, sparks (or just light -- I'm not sure what) came
from the outside unit when it started, seemingly from the motor. *The
outside unit seems to be just a fan surrounded by a radiator. *(I'm
guessing the compressor is inside.) *I wasn't close when it happened
-- but I did see it light up (it was night time, so I could see it) --
which tells me something either emitted sparks, or got red hot before
the circuit breaker blew again.

As I understand it, it's a three phase motor but powered by one phase
power, and the condensor helps this arrangement work. *If a motor
can't start, it'll draw a massive amount of current and get hot, fast.
My theory is that the condensor wasn't working properly and so the
motor couldn't start, the winds got red hot in a second before it the
breaker blew. *But it's just a theory -- I've little actual experience
with this motor/condensor setup, though I am somewhat familiar with DC
motors. *The motor seems to spin freely.

I only have one case of failure to work with, but I'm guessing that
the condensor got wet and that prevented it from working properly so
it couldn't help the motor start. *My current plan is to clean the
condensor off, make sure it's all waterproof, and then run with it. *I
guess since the motor is outside, with nothing flammable nearby, and
it does have an effective breaker, there's little actual risk of fire
-- at most, it'll fry the motor.

--
Doug McLaren,
If Bill Gates had a penny for every time Windows crashed...
.oh wait, he does.

The flash you saw may have been normal. The fan and compressor are
both started by a large relay. Depending on where it is located and
how well all the covers are installed it is possible you saw it arcing
when it tried to start the unit. The relay has open contacts so it is
possible to see a flash in the dark.

Both the fan motor and the compressor motor will have capacitors, aka
condensors. If both are now running then the capacitors are most
likely good. They tend to fail competely and when they do the motor
in question doesn't run. The fan also tends to fail completely and
is obviously failed when it won't run. Since your is running odds are
it is good. The relay is a dual pole with both hots running through
it. It is pulled by a 24vac power over a small line form the air
hanlder. The fan motor is 120, the compressor is 240. The compressor
motor and the actual compressor it's self are sealed inside a big
roundish can in the middle of the unit. The can is two halves welded
together so the compressor motor is not servicable.

The compressor can become hard to start. It has to start under a load
even normally because the refrigerant is already at a significant
pressure. Various problem situations can also cause the refrigerant
to enter the compressor in a liquid state and then it really has a
hard time starting. Those problems can come and go based on outside/
inside temps and what the inside airhandler is doing. So the fact
that it appears to be working fine now is not an indication of clear
sailing. The compressor also has a overheat/overload safety device in
it. That too is not servicable. If the compressor is having too much
trouble starting that will kick out. You don't want to keep causing
that ovcerload to kick as it will get weak just like letting a breaker
pop over and over.

You can certainly look around inside with the service cutoff turned
off. But you really need someone with some equipment; guages, clamp
on current meter, thermometer to take a look at. A good service tech
will check the pressures, temps outside and inside, as well as the
compressor start up and run current.