Outside air conditioner unit blew circuit breaker, sparked ...

Posted by Doug McLaren on October 27, 2009, 1:19 pm

So, last week, we found that the air conditioner wasn't working. The
inside blower was working, but it was blowing room-temperature air.

I tracked the problem down to the big (50 A) circuit breaker being
blown. I switched it back, and it immediately blew again (well, in
about a second) and I heard a noise from the outside A/C unit (on the
other side of the house, so I couldn't see it.)

So I got my wife to do the circuit breaker again while I was watching
the outside unit. The motor glowed or sparked or something -- light
came out. I wasn't that close, so I'm not sure exactly which. I'm
also note sure what the fan did.

It was raining, so I left things off, went inside.

I came back out the next day, sunny skies, and tried it again, this
time being close to the unit so I could see exactly what happened.
And it started up fine, no problems. Turning it off again, I saw that
the fan spun pretty freely -- it doesn't seem to have problems with
the bearings (as I've had in other appliances.)

So now it seems fine. But I'm reluctant to actually turn it on. Yes,
the circuit breakers will protect me from future problems, but I don't
like relying on it.

I'm not much of a handyman, but I could replace the motor and/or
condensor easily enough -- it's easily accessible. And of course I'll
have everything off and the circuit breaker off if I try. This is
about 10 years old, and living in Texas, it gets a lot of use.

But should I? Or should I just check that water isn't getting in
somewhere?

--
Doug McLaren, dougmc@frenzied.us

Posted by N8N on October 27, 2009, 2:37 pm

> So, last week, we found that the air conditioner wasn't working. =A0The
> inside blower was working, but it was blowing room-temperature air.
> I tracked the problem down to the big (50 A) circuit breaker being
> blown. =A0I switched it back, and it immediately blew again (well, in
> about a second) and I heard a noise from the outside A/C unit (on the
> other side of the house, so I couldn't see it.)
> So I got my wife to do the circuit breaker again while I was watching
> the outside unit. =A0The motor glowed or sparked or something -- light
> came out. =A0I wasn't that close, so I'm not sure exactly which. =A0I'm
> also note sure what the fan did.
> It was raining, so I left things off, went inside.
> I came back out the next day, sunny skies, and tried it again, this
> time being close to the unit so I could see exactly what happened.
> And it started up fine, no problems. =A0Turning it off again, I saw that
> the fan spun pretty freely -- it doesn't seem to have problems with
> the bearings (as I've had in other appliances.)
> So now it seems fine. =A0But I'm reluctant to actually turn it on. =A0Yes=

> the circuit breakers will protect me from future problems, but I don't
> like relying on it.
> I'm not much of a handyman, but I could replace the motor and/or
> condensor easily enough -- it's easily accessible. =A0And of course I'll
> have everything off and the circuit breaker off if I try. =A0This is
> about 10 years old, and living in Texas, it gets a lot of use.
> But should I? =A0Or should I just check that water isn't getting in
> somewhere?
> --
> Doug McLaren, dou...@frenzied.us

If it coughs when raining and works when dry, I would definitely
suspect a water intrusion issue. However you may want to have an HVAC
guy look at it anyway - a 50A, 240VAC circuit can knock you back a bit
if you're not careful. Depends on your comfort level working with
this stuff.

nate

Posted by jeff_wisnia on October 27, 2009, 5:05 pm

N8N wrote:

>>So, last week, we found that the air conditioner wasn't working. The
>>inside blower was working, but it was blowing room-temperature air.
>>I tracked the problem down to the big (50 A) circuit breaker being
>>blown. I switched it back, and it immediately blew again (well, in
>>about a second) and I heard a noise from the outside A/C unit (on the
>>other side of the house, so I couldn't see it.)
>>So I got my wife to do the circuit breaker again while I was watching
>>the outside unit. The motor glowed or sparked or something -- light
>>came out. I wasn't that close, so I'm not sure exactly which. I'm
>>also note sure what the fan did.
>>It was raining, so I left things off, went inside.
>>I came back out the next day, sunny skies, and tried it again, this
>>time being close to the unit so I could see exactly what happened.
>>And it started up fine, no problems. Turning it off again, I saw that
>>the fan spun pretty freely -- it doesn't seem to have problems with
>>the bearings (as I've had in other appliances.)
>>So now it seems fine. But I'm reluctant to actually turn it on. Yes,
>>the circuit breakers will protect me from future problems, but I don't
>>like relying on it.
>>I'm not much of a handyman, but I could replace the motor and/or
>>condensor easily enough -- it's easily accessible. And of course I'll
>>have everything off and the circuit breaker off if I try. This is
>>about 10 years old, and living in Texas, it gets a lot of use.
>>But should I? Or should I just check that water isn't getting in
>>somewhere?
>>--
>>Doug McLaren, dou...@frenzied.us

>
>
> If it coughs when raining and works when dry, I would definitely
> suspect a water intrusion issue. However you may want to have an HVAC
> guy look at it anyway - a 50A, 240VAC circuit can knock you back a bit
> if you're not careful. Depends on your comfort level working with
> this stuff.

Rather that "comfort level" it might have been better to write
"knowledge and experience".

Fools rush in where......

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10e12 furlongs per fortnight.

Posted by Doug McLaren on October 27, 2009, 5:20 pm

| > If it coughs when raining and works when dry, I would definitely
| > suspect a water intrusion issue. However you may want to have an HVAC
| > guy look at it anyway - a 50A, 240VAC circuit can knock you back a bit
| > if you're not careful. Depends on your comfort level working with
| > this stuff.

|
| Rather that "comfort level" it might have been better to write
| "knowledge and experience".
|
| Fools rush in where......

Anything I do, the A/C will be off, the circuit breaker will be off,
and the switch near the outside unit will be off before I go near the
thing.

I'm not an electrician, but I know that much :)

A condensor is just a capicator, and it can store voltage as well,
though being connected directly to the wirings of a motor I wouldn't
expect it to store anything more than a second. But I'll short it out
with an insulated screwdriver before I touch it just to be sure.

I'll also check for voltage with a multimeter in HV mode before I
touch anything. I really wouldn't expect any, but I'll check.

And I'll try to work with one hand in my pocket, just in case.

I think that covers all the electrical safety issues.

--
Doug McLaren, dougmc@frenzied.us
"I am returning this otherwise good typing paper to you because someone
has printed gibberish all over it and put your name at the top."
-- English Professor, Ohio University

Posted by jamesgangnc on October 27, 2009, 3:36 pm

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.

Be careful even messing around with the wire terminals at the
compressor. Turned off it still has at min of 100 psi pressure inside
it. Sometimes those terminals get old and will blow out the side when
you start messing around wth them.

The compressor takes a whole lot of current to start up. There are
hard start kits that can be added to ones that have trouble starting.
You orbably ought to get an hvac guy to look at it. He can put a
clamp meter on it and see how much current it is drawing on start up.

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