Central Air Conditioner will not start

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Hello,
Recently when I went to turn on the central air I noticed that the air coming out of the unit was not cold. It was right before I went to bed so I didn't check the compressor outside to see if it was running. today I had some time, and I fired up the AC and checked outside, and noticed that the fan was not running.
I checked the breaker and flipped and a couple of times, this did not turn it on.
I checked the high voltage and low voltage wires at the compressor and I was getting a reading on the high voltage, but my volt detector could not pick up a hot wire on the low voltage line.
No obvious obstructions to the fan or motor, no wire inside the unit seemed worn or torn, and was properly connected.
I can hear a faint hum at the compressor as if a motor is trying to run but it is not actually running.
This is a very old unit, it's a GE and I am wondering if it came with the house when it was built in the late 70's.
Anyone have any idea what could be the cause or perhaps a start in the right direction? I'm not sure I can afford a new unit right now..and I can only imagine how much repairs may cost to an old unit like this.
thank you
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That hum is probably the 24v contactor pulled in. Sounds like you don't have 240V to the outside unit. It's unlikely both the compressor and condenser fan are bad. I would check the capacitor. You sure there is no disconnect box outside, that might be interupting the line voltage? Hard to say unless you can take some electrical readings. I would double check you have 240V across your contactor, and 120v from each side to ground. Then check to see power leaving the contactor.
Could be as simple as a dead bug preventing the contactor to fully close. Does your tester just glow red? It should glow red on both line wires. The 2 control wires probably can't be read with your meter.
-Canadian Cool
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Come on by new one don't be cheep skit

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"Cheap Skate" not skit

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snipped-for-privacy@gmail.com wrote:

There should be two "high voltage" wires for 240V. Did you check both?
Did you check for (low) control voltage across the contactor coil?

Maybe it only has 120V because one side of the line is dead.

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Thanks for the help all. Now that I think of it..I believe there was two high voltage lines, and I am pretty sure the volt detector was pinging on both, but I am not a 100%. It's dark out or i would check now. I'l check the name plate and make sure it is rated for 240V. There are definitely two wire runs running to compressor in conduit and sheathing. One is a higher guage..and I am assuming is the lower voltage..which my voltage detector is not picking up..but I am not sure if it is capable of picking it up..like some have mentioned before. I think I really need to invest in a proper meter.
I am a little confused on the contacter, I am not sure i know what you are talking about there, or what it looks like other then a web photo and I doubt I checked to see if there was any conductivity there. I remember seeing the capaciter, and a couple of other electrical sort of things I was unfamiliar with.
There is definitely not any sort of disconnect box..I double checked in the crawl space where the wires run, and it runs straight from the compressor to the breaker. And there is nothing on the outside that I can see. Like I said it is a pretty old unit.
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Which is why there are HVAC companies in your area... why not call one?
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I actually did contact one, as it it seems like it is starting to get a little over my head. But is it such a problem to understand and maybe even fix something that I now own. Maybe I posted this on the wrong forum..I googled the problem and this group came up. I apologize for my newness.
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Just understand that a lot of fatalities happen at home because people don't think that what they're doing is dangerous.
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snipped-for-privacy@gmail.com wrote:

There are a lot of j*ck*sses here who think it's their duty to harass the uninitiated. I don't know why.
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Hide quoted text -

I see you offered a lot of help in your reply. LOL
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CJT wrote:

You are a fine example...
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snipped-for-privacy@gmail.com wrote:

unlikely -- the heavier one will run from the breaker box to the compressor unit, and carries the 240V; the thin one will carry the low-current, low voltage control signal from the thermostat
which my voltage detector is not picking up..but I am not

A contactor is a relay that controls the electricity to the compressor based on a thermostat-level (almost always 24VAC) signal. It's typically mounted on an inside panel of the unit.
I

If you are that unfamiliar, you might be out of your league.

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On 10 May 2007 15:26:27 -0700, snipped-for-privacy@gmail.com wrote:

Wait until it gets about 90 degrees outside. Then start flipping the breaker back and forth till it comes on. It may takes days before the breaker actually makes contact. Dont give up. Bubba

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Is there some sort of rhythmic pattern I need to follow as well. Maybe I need to bite the other end of the wire while someone flips the breaker back and forth in 4/4 time huh?
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Yup. Now you're learning.
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According to "23rd Annual Portrait of the U.S. Appliance Industry," Appliance Magazine, September 2000, The life expectancy in years for "Air conditioners, unitary" are; Low 8, High 19, and Average 13. With the huge amounts of energy your wasting trying to run that Jurassic system, how can you afford NOT to replace it. When I replace an ancient system like that for my customers, its not unusual for their light bill to get reduced by as much as 60%.
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Yep..yep. I think it's day is done, even if I get it fixed it will be life support for sure.
Godamn y'all are way too candid in here.
I can smell harshness on the newbs from a mile away. I feel bad for the other lost souls who stumble on to this forum in their enternal pursuit of do-it-yourselfdom like I just did.
Definitely not a warm and fuzzy in here.
But I appreciate all the help nontheless bullshit included.
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With all due respect, it sounds like you do not know enough about electricity to be sticking your hands in the electrical cabinet.
As everybody else has said, you need to get somebody there who knows what they are doing before you kill yourself.
I am an electrician, not an HVAC tech. To me, it sounds like your contactor is not pulling in fully, if at all, and the hum you detect may be the contactor buzzing. It will probably burn its coil out if it is energized with the proper (24 VAC?) and rusted/jammed can't pull in.
What I said above is not a suggestion for you to look into any more than a doctor telling you you you have a hernia and you cutting yourself open to check it out. :-)
As a matter of fact, I should have just stayed lurking in the background, as this trys to be a group for HVAC techs to share their experiences an not help homeowners DIY.
Finally have a rainy day here and got back to look at this group; its been busier than normal!
Bob
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DIMwit wrote:

One could only hope... maybe forget the hernia and go with the biggie - brain surgery!
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