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outside a/c unitfan will not turn on without giving it a andwon't blow cold air

outside a/c unitfan will not turn on without giving it a andwon't blow cold air

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  #1  
Old 08-28-13, 10:26 AM
J
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outside a/c unitfan will not turn on without giving it a andwon't blow cold air

came home from work one day and my AC was on but it was 86 degrees inside the house so I checked the outside unit in the fan was in on. so I took a stick and push started the fan cause I can hear it trying to draw electricity but when I push started it it kept on turning but only at about half of its normal speed and it was still not blowingcold air.I've got to be losing power somewhere but I'm not sure exactly where. Can someone please give me some advice on where to go from here.
 
  #2  
Old 08-28-13, 10:44 AM
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More than likely it is the run capacitor in your condenser (outside unit). What type of system do you have: heat pump or air conditioner? I have attached a photo of what the run capacitor looks like. If your run capacitor has three sets of terminals it is a dual run capacitor for the condenser fan and the compressor. It is possible you could have a separate capacitor with only two sets of terminals. If you feel confident you can remove the panel that houses the controls for your condenser. You will need to shut the power off at the disconnect and remove the screws to access the panel usually with a 5/16" nut driver or socket. If you find the run capacitor you can visually observe it to see if the top of it is bulged out or has leaking fluid. That is a classic sign of a bad capacitor. Fortunately, the part is relatively easy to find and replace and not too bad on price depending on where you purchase it. Do not touch the capacitor without discharging it as the capacitor can give you a good jolt. If you will post what make and model you have and some nice clear photos there are a lot of good people here who will try and help you.

If you own a multimeter and know how to use it there are some basic tests you can do to troubleshoot the system if it is something beyond the run capacitor.
 
  #3  
Old 08-28-13, 10:47 AM
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Usually, when the condenser fan has trouble starting, but runs when "pushed", it's the capacitor that's defective. Turn off the power to the outside unit and remove the access panel (panel that covers the electrical components. Most outside units have two capacitors, one for the compressor and another for the condenser fan, however sometimes they're combined in a dual capacitor (two capacitors in one "can"). Trace the wiring (or look at the wiring diagram) to find which capacitor goes to the fan. Make a note of the capacitance and voltage, and purchase a replacement capacitor.

Once you have the replacement capacitor, be sure the power is turned off, and take a screwdriver and short between the terminals of the old capacitor (to bleed off any residual charge). Disconnect the wires from the old capacitor (make a note of where they go if it's a dual capacitor), replace the capacitor with the new one, and connect the wires up the same as the old capacitor was wired. Turn on the power, and with any luck your A/C will be operational again.

Note, don't run the A/C with the condenser fan not working (or running slowly) as that will likely overheat the compressor (fan cools the condenser coil and the compressor).
 
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Old 08-28-13, 11:09 AM
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I'm hoping it is the capacitor, which is a dual capacitor because I only have one,but I did look for the buldge on top and there wasn't one or any leaking fluid. Now once I get my fan going you can hear about every 30 seconds the compressor, that's what I'm guessing it is, trying to draw the power to get it started but you can never hear it kick on it just Buzz's for a second and then it stops. Its a trane a/c but I'm not sure of the model number and I'm at work right now but my dad took some pictures of the capacitor and is going to try to get one and see if that's the problem. the house was built in 2004 so the AC is 9 years old but when I bought the house in 2010 I had to have the AC man come out, since it was still under warranty for 12 months, andif I'm not mistaking he replaced the capacitor then or it was something to do with my compressor. Thanks for the input guys and I hope that's the problem because all the wiring looks good not damaged.
 
  #5  
Old 08-28-13, 11:14 AM
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You can't always tell by looking that the capacitor is bad. The best way to check it is to measure the capacitance to see if it is within specs with a multi-meter that has that capability. If the fan is not operating properly the compressor will shut down on thermal overload or trip a pressure switch. As far as a replacement capacitor there are some numbers to look for on the label. It will be something like 40/5uf or 45/7.5uf and 370VAC or 440VAC. Take those numbers and you can order a replacement on-line or if you live where they have a Grainger's or Johnstone Supply you can go there and get a replacement.
 
 

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