A/C problem, need help ASAP

Page 2 of 4  
wrote:

You're right! I should probably think of it that way.
Darn, now I'll be afraid even to plug in a lamp.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Danny G. writes:

Where you at? 13 KVAC hereabouts.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I was just teasing about the transformer thing. 8)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

But now I'm sitting in the middle of the room, as far from the outlets as possible. I had to get an extension cable for my computer keyboard.
And there's that asbestos, too.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Trim this tree.
--

Christopher A. Young
You can\'t shout down a troll.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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
On Thu, 03 Aug 2006 02:37:39 GMT, Ignoramus2645

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Well, the contactor's apparently bad. Start there. Been there, done that. Respectfully, Ron Moore
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Does this happen to be San Diego, Ron Moore?
Barry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ignoramus2645 writes:

Two capacitors, in one can, with a common terminal.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yes, that's right. You got it 100%. Here's the schematic:
http://igor.chudov.com/tmp/AC-Compressor/diagram.jpg
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Some new developments.
1. The main 24VAC coil contactor is fine, I must have mis-measured something.
2. 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.
3. 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)
2. 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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ignoramus2645 wrote:

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.
--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form snipped-for-privacy@prodigy.net.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

He's better at the guessing part. I suggest he wears a blue shirt tomorrow, and white socks.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yea. Great idea. Here's the diagram:
http://igor.chudov.com/tmp/AC-Compressor/diagram.jpg
It is actually very straightforward.
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ignoramus2645 wrote:

It's also rather sad that the protective devices are "optional" or "accessories".
Pete C.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

    And -- you can see the time delay module under the varnish (or whatever) at the bottom right of the diagram -- in series with the contactor coil, and an optional switch in which the high pressure side of the refrigerant pump can prevent start even if the timer has timed out. (But -- that is described as "optional", and the delay timer (as much as I can make out under the varnish) is not described as "optional", but it *is* described as "accessory" -- so I suspect that you have two failures -- the compressor, and the delay timer which induced the compressor failure, and which will induce it again if not replaced when the compressor is replaced.
    It looks as though there is only one set of contacts in the contactor, and the other set of terminals serves simply as a terminal strip to carry the other side of the 240 VAC over without switching it.
    This is *not* a good time of the year to have an air conditioner fail -- and also not a good time to try to get a licensed professional out to work on it.
    You might save one round trip (probably with significant delays) if you warn them ahead of time that the compressor is likely dead. If you can, dig up the numbers from the compressor case -- or if you can't get to that, at least the model number of the overall device.
    Good Luck,         DoN.
--
Email: < snipped-for-privacy@d-and-d.com> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I am now convinced that it is true, the compressor unit is dead. These guys that service my equipment are in my town, a trip should not be too much for them, and also, after looking at the outside unit, I think that I want something better.
i
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Notice in series with the "C" terminal on the Compressor, there is an overload device. This is a self reseting current limit that most likely is part of the plug that connects to the C, S, and R terminals of the compressor (these stand for Common, Start and Run). Or it is a separate device but in thermal contact with the compressor can. Klicks-on is a Texas Instumentcompany that makes these. The diagram indicates "if used" but I believe it has to be there to protect the compressor motor in the case where it has a locked rotor from differential pressure, and it does not have enough starting torque. Pull the C,S, and R plug, and perform a resistance measurement between C and S and C and R. These should be less then 10 ohm measurements. SteveK Ignoramus2645 wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Steve, mine does not look like a plug, more like three terminals.
I am not sure if there is an overload.
i

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.