Central A/C outside unit not starting


  #1  
Old 07-31-08, 11:41 AM
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Central A/C outside unit not starting

Our central a/c system recently (yesterday) went out. When the thermostat was turned on to cool the outside unit wouldn't start and there would only be a buzzing sound at the unit. When the contactor switch is engaged (pressed in) with a screw driver the unit turns on as normal. I have the contactor switch replaced and am still getting the same results, could it be possible the thermostat isn't delivering enough power to engage the switch? If so what are some simple solutions?
 
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Old 07-31-08, 12:07 PM
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Originally Posted by KSB28
Our central a/c system recently (yesterday) went out. When the thermostat was turned on to cool the outside unit wouldn't start and there would only be a buzzing sound at the unit. When the contactor switch is engaged (pressed in) with a screw driver the unit turns on as normal. I have the contactor switch replaced and am still getting the same results, could it be possible the thermostat isn't delivering enough power to engage the switch? If so what are some simple solutions?

Get a voltmeter and check the coil voltage to the compressor contactor. As in all electrical systems, the problem will show up in power, load, wire, or control and possibly in combination.
If you are not an experienced service tech, avoid the use of jumper wires.
 
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Old 08-16-08, 09:52 AM
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Tempstar Outside A/c Unit Not Working

i just bought this brick home this year and the A/C Unit went out Yesterday. The fan doesnt turn and when I went outside i heard it humming then it just stopped. Any Answers? Thanks
 
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Old 02-11-09, 08:21 PM
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i too have the same issue, some buzzing noise coming from the outside unit.
the house is 10 yrs old, new payne outside unit with heat pump.
inside unit is trane.
we had the ac repair folks out again. they just replaced the outside unit due to the coil leaking freon from the old trane unit.
now the new unit is installed worked great for about 2 weeks.

so they just came out tonight, replaced the contacts on the outside and the transformer on the inside air handler. same problem.
now they state that we need to install another transformer to get more power to the outside unit. thats a total of 2 transformers.

does this sound right??
any advice??
thanks

btw i tried to search, but could not find
 
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Old 02-14-09, 09:56 PM
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anyone???GI2GI2

so the guy came out today and installed a bigger transformer instead of adding a additional one.
works, but for how long?
it hums but not so loud now.
maybe its fixed???

thanks
 
  #6  
Old 02-22-09, 02:10 PM
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AC out

Hi, I'm a diy hack but I have saved myself a lot of money.

I have a lot of AC stuff, home, store coolers. I'm not there to test but most times my compressors that fail are brought back to life with a new fan motor. Costing about $70 for outside condensers at your local AC parts supplier. Another common piece is the start capacitor (careful !! these things store power after being turned off and can bite you !) they run around $12. Prices are based on the units I have.

Make sure you write down where the wires go, if you reverse them you may damage your system. Other than that it's cheap and easy.

Again, I'm not there to test and I'm not licensed. I just have real life experience. No guarantees
 
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Old 02-23-09, 06:37 PM
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Originally Posted by KSB28
Our central a/c system recently (yesterday) went out. When the thermostat was turned on to cool the outside unit wouldn't start and there would only be a buzzing sound at the unit. When the contactor switch is engaged (pressed in) with a screw driver the unit turns on as normal. I have the contactor switch replaced and am still getting the same results, could it be possible the thermostat isn't delivering enough power to engage the switch? If so what are some simple solutions?
The "buzzing" can be caused by low control voltage to the coil of the contactor, this can be caused by wrong size of control wiring. or failing transformer or low high voltage to transformer.
Check the voltage at the contactor. Should be 23-25 volts ac.
Let me know.
 
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Old 02-23-09, 06:41 PM
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Originally Posted by MTOYOTAOWNR
i too have the same issue, some buzzing noise coming from the outside unit.
the house is 10 yrs old, new payne outside unit with heat pump.
inside unit is trane.
we had the ac repair folks out again. they just replaced the outside unit due to the coil leaking freon from the old trane unit.
now the new unit is installed worked great for about 2 weeks.

so they just came out tonight, replaced the contacts on the outside and the transformer on the inside air handler. same problem.
now they state that we need to install another transformer to get more power to the outside unit. thats a total of 2 transformers.

does this sound right??
any advice??
thanks

btw i tried to search, but could not find
Well sorry to bust your bubble but the ac contractor has done you no favors. You should never mix and match when it comes to HP's the coil in your Trane is surely not rated to preform with your new Payne outdoor unit. A 40va transformer is more than enough for most home units with normal line lengths. See my other post about buzzing noise.
 
 

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