Disconnected electricity, reconnected- now compressor won't kick on


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Old 09-01-14, 09:09 PM
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Question Disconnected electricity, reconnected- now compressor won't kick on

I had to re-route the power to the compressor on my AC system so I disconnected the breaker, re-ran the run then hooked it back up. I am confident that I reconnected the breaker properly (I took a photo of the connections before hand to double check). I've checked that there is current to the compressor (there is), but it isn't kicking on. The thermostat says "cool" and the temp is a couple degrees above the set point. The blower does come on, just NOT the compressor. It was running earlier today, so the odds of it crapping out coincidentally seem very slight.
There is a physical disconnect outside the house, but no breaker outside that I can discern. Our local utility has one of those radio controlled boxes to remotely turn off our unit during peak times, but this is not one of them (late evening).
What could be keeping the compressor from kicking on? I tried turning everything off, then back on again, but to no avail...
 
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Old 09-01-14, 09:13 PM
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I've checked that there is current to the compressor (there is)
You didn't use a non contact tester did you?
 
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Old 09-01-14, 09:36 PM
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You stated you had power to the compressor. With your multimeter set to VAC, do you have 240V to the contactor across L1 and L2 terminals and 240V across T1 and T2 coming out of the contactor? Also test voltage across the two smaller terminals on the side of the contactor while the thermostat is calling for cool. Those tests would give you a start as to where your problem lies. You stated the blower does come on. Did you mean to say the condenser fan comes on? I have attached a diagram of the voltage testing points I have mentioned. Be extremely careful as voltages are lethal!!!!
 
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Old 09-01-14, 10:00 PM
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I don't have a meter, just a current tester (the type that picks up the electric field and beeps). No, I meant the blower of the furnace. Nothing happens on the unit outside the house.
 
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Old 09-01-14, 10:03 PM
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In order to diagnose your problem you are going to need at least an inexpensive voltmeter.

Did you also disconnect the small thermostat wiring to the condensor ?
 
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Old 09-01-14, 10:14 PM
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You really need a multi-meter to properly test the presence or absence of voltage. Personally I would never rely on a proximity voltage tester as too many variables can skew the test. Even if the voltage tester is working properly it will only tell you that you do have voltage in the vicinity but not how much or exactly where it is. As you can see by the diagram I attached previously, a voltage tester as you used, would be of no use to determine if the proper line and control control voltages are present at the condenser to allow the system to work properly. Did you try resetting the breaker a couple of times to see if it would get the unit to fire back up? The tests I showed in the diagram previously posted would quickly tell you many things about the status of your electrical supply to the condenser.
 
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Old 09-01-14, 10:18 PM
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If you have a square D breaker type disconnect there is at least a 50% chance that is your problem. Only one leg of power is getting through and your volt stick sees power but you do not have both 120 volt legs. (You need 240 volts)

I dread turning off that model and usually inform the homeowner that there is a 50% chance that it will require replacement if I turn it off to service the unit if the disconnect is more than a few years old.

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I prefer to hunt down the breaker and not touch that thing whenever possible.
 
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Old 09-02-14, 05:49 AM
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Noted on the voltmeter. I did not disconnect the thermostat wire. I only disconnected the power at the breaker box and then reconnected in the same way. I suppose it is possible that one of the lugs on the breaker isn't making good contact, but I'm at a loss. HVAC tech should be out this afternoon to look at it. Fingers crossed I didn't somehow fry my compressor. With that said it is a no-name 9 year-old 3 1/2 ton unit. Any one have any idea on the life expectancy of these things?

Houston204- I don't recall who the disconnect is from. Your pic looks like one of a breaker though so I'm confused. My disconnect is literally a big pull out to create a gap in the current. That said, the box it lives in is almost completely corroded away.
 
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Old 09-02-14, 06:06 AM
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Your disconnect is probably one similar to the attached photo. When you re-routed the power to the compressor did this include removing wires and re-connecting them inside the disconnect box? The disconnect box definitely needs to be waterproof so if it is corroded I suggest you replace it first chance. I also suggest you re-check that the breaker you removed and replaced is fully seated onto the lugs in the electrical panel as well as the connections to the bus bar are tight. Multi-meters can be found for as low as $5.99 at the discount tool store. They aren't the best, of course, but they will allow you to do the tests outlined in an earlier post. They are also invaluable for many household chores such as testing fuses, batteries, electrical outlets and automotive electrical testing and will pay for themselves many times over.
 
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Old 09-02-14, 06:59 AM
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If you buy a multimeter get an analog not a digital. Digitals can be influenced by induced or capacitive voltages. $8-$15 is all you need to spend.
 
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Old 09-02-14, 07:45 AM
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Nothing was disconnected outside; only at the main breaker box inside. I'm not home at the moment so I can't test anything. Will post when I learn more this afternoon. And, yeah I should replace the corroded outdoor box.
 
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Old 09-02-14, 08:02 AM
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Ok, then that would point to the connection only at the breaker and definitely will help facilitate troubleshooting your issue.
 
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Old 09-02-14, 02:09 PM
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Okay. Tech came out and looked... Bad leg. Only getting 110V. This explains why my tester was showing current. Turns out I had a bad breaker. For some reason taking that breaker out to disconnect the leads killed it. (It was pretty old though.) Circuit tester would have saved me some money...
 
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Old 09-02-14, 02:24 PM
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Glad you found the problem. I was hoping you would be able to save money by borrowing a multimeter or purchasing one to do the testing which would have identified the problem in less than a couple of minutes. The good thing is the problem was identified and averted a major safety concern.
 
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Old 09-02-14, 06:27 PM
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True. Though I was only charged $20 since I have one of their service plans...
 
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Old 09-02-14, 07:29 PM
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No doubt that is a decent price to pay for that repair.
 
 

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