A/C problem, need help ASAP

[Ignoramus2645]

I have a central A/C. Around when there was a thunderstorm, electricity flickered about 2-3 times in our house.

Now our A/C is not working. The inside is all fine, the fan runs etc.

I am doing investigation and will post in this thread, but the breaker popped and any attempt to reset it pops it again. I tried to measure amps with my ammeter, it was quite hard to do due to breaker popping soon, but the highest measure I got was about 200 amps.

I am going to open up the case now to have a quick look, I will be running back and forth. My hope is that it is something simple like capacitor shorted, but it easily could be worse (eg motor shorted).

i

[Noon-Air]

Get an electrician to check your shorts

[Oscar_Lives]

Have your buddy hold the breaker handle over for a while so the current can stabilize and you can get a better reading.

[PJ ;-)]

Absolutely. 200 amps is a lot of punch.

[Ignoramus2645]

It is quite obviously not very relevant, but there is very solid 24 VAC as input to the contactor's coil.

One pair of contacts (across the contactor) measures 0 ohm. Another pair, strangely, measures infinity, which is quite strange as the contactor ought to be closed for a power fault like this to occur (barring some very strange troubles). I left the outside unit due to the rain that resumed, will come back there soon.

I am not used to seeing such strange contactors, all contactors that I dealt with, to date, were three pole contactors for 3 phase motors.

Also, can someone explain me why the capacitor has three sets of terminals. What is the purpose of the third terminal. Thanks.

i

[PJ ;-)]

Funny, but OMFG

[Ignoramus2645]

My shorts are pretty wet by now, from the rain and wet grass.

As far as the wiring, I would like to check out some things by myself (I am not a big stranger to electricity, built my phase converter blah blah).

i

[Ignoramus2645]

My shorts are pretty wet by now, from the rain and wet grass.

As far as the wiring, I would like to check out some things by myself (I am not a big stranger to electricity, built my phase converter blah blah).

i

[Ignoramus2645]

My shorts are pretty wet by now, from the rain and wet grass.

As far as the wiring, I would like to check out some things by myself (I am not a big stranger to electricity, built my phase converter blah blah).

i

[Ignoramus2645]

I tried it, and I think that the breaker is good enough to reset despite that. In any case, it is kind of pointless, as I know that the current is too large and lasts too long.

I tried asking my wife to turn on the CB while I was outside, I heard some humming noise and then stop. I will wait a little until rain subsides and will go back.

i

[Ron Moore]

Well, the contactor's apparently bad. Start there. Been there, done that. Respectfully, Ron Moore

[Ignoramus2645]

Hi Ron.

I think that I was wrong. The contactor is OK. I must have mismeasured something. It has zero ohms across bost pairs of contacts.

I am going to post a little update, it is a little more apparent to me -- see my separate post.

i

[Ignoramus2645]

Some new developments.

1. The main 24VAC coil contactor is fine, I must have mis-measured something.

1. I understand why there are three terminals on the capacitor. There are really two capacitors in one "can". They share a common. One capacitor is for fan and another is for the main compressor motor.

2. If I disconnect one lead to the capacitor (a fat blue lead), then, if my wife resets the breaker, the cooling fan starts up just fine and I hear humming noise from the motor. I did not let that continue for much more than 2 seconds.

My conclusion is that most likely, the capacitor for the main motor is shot.

Q U E S T I O N S:

1. Anyone know how to calculate required capacitance by "rated amps" of the motor? (I realize that motors are all different, but I need some way to guesstimate)

1. Do the two coexisting caps share a common terminal, or does one of them have one contact on top and another being the (grounded) can?

Answers will be appreciated.

More to follow.

i

[CJT]

There ought to be a diagram somewhere, and some markings on the capacitor, that will tell you what you need to know. Anything else is just guessing.

[Oscar_Lives]

Turn up the "squelch" knob on the CB. That ought to stop the humming and noise.

10-4 good buddy!

[Cydrome Leader]

He's better at the guessing part. I suggest he wears a blue shirt tomorrow, and white socks.

[Ignoramus2645]

Sounds like you are not going to be helpful.

i

[Barry]

Does this happen to be San Diego, Ron Moore?

Barry

[Oscar_Lives]

You get what you pay for. Hire a tech and get it fixed. hang out on the world wide web and be entertained.

Cheap f*ck.

[Ignoramus2645]

Yea. Great idea. Here's the diagram:

It is actually very straightforward.

i