Lennox A/C troubleshooting? - http://www.hvacmechanic.com/ Forums
Original message
| sirphobos1
 |  "Lennox A/C troubleshooting?"
, posted Fri 13 Jun 10:52  
Hi all, I just recently purchased my first house and i'm having trouble with the A/C unit outside. First off, it's a Lennox 10ACB24-11P. I'm assuming it was built with the house, in 2001.
Here's my problem. On the outside unit, when the thermostat is set to cool, and the unit turns on, after about five minutes or so, the fan will cut off, and the compressor will continue to run. Here's a list of things we've tried to troubleshoot the problem:
-replaced fan motor
-replaced cap
-cleaned contactors
-ran old motor with new cap
-disconnected compressor from power and still watched the fan stop running.
-ran separate caps for the compressor and fan, and still had the fan cut out.
i'm out of ideas. Any help would be great.
sorry for posting in general and in here, i just discovered this sub-forum.
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Replies:
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| sirphobos1
| "Re(1):Lennox A/C troubleshooting?" , posted Mon 23 Jun 13:35
i had an HVAC specialist come over last friday and look at it. He declared it was the motor, and said that more than likely i had been given a bad replacement motor, so I have a new one on the way. another update when i get this motor installed...
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| | marchvac
| "Re(2):Lennox A/C troubleshooting?" , posted Mon 23 Jun 21:47
What is the horsepower and RPM of the motor that is in it.
Be careful sometimes you don't get a second chance
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| | sirphobos1
| "Re(3):Lennox A/C troubleshooting?" , posted Tue 24 Jun 10:58
1/6 hp
1075 rpm.
i bought this one oem, vs. grainger where i got the last one. (the specs were the same, but who knows..)
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| | marchvac
| "Re(4):Lennox A/C troubleshooting?" , posted Tue 24 Jun 19:46
That is the correct motor. When you install the new one make sure you install a new capacitor and the blade sits at the correct height. When you start it make sure it goes the rite way and check the amperage to make sure it is within spec.
Be careful sometimes you don't get a second chance
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| | sirphobos1
| "Re(5):Lennox A/C troubleshooting?" , posted Thu 26 Jun 09:18
it works! been running healthy for the past 15 hours now. it was indeed the motor.
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| sirphobos1
| "Re(1):Lennox A/C troubleshooting?" , posted Tue 17 Jun 08:36
Ran another test last night with another new cap, and original motor. put meter on contactor, showed a steady 238 vac, with occasional 239. still retained 238vac after fan kicked off. took much longer to do, either on account of it not being as hot, or some other reason.
i'm starting to lean towards the motor is crap, and the one we got to replace it was the wrong one....
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| | marchvac
| "Re(2):Lennox A/C troubleshooting?" , posted Tue 17 Jun 20:32
You have to check the amperage while the motor is running. Make sure it is the same as the rating plate on the side of the motor. Did you install a Lennox replacement. Some of the motors have a different rpm and will make the motor over amp and shut down.
Be careful sometimes you don't get a second chance
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| | marchvac
| "Re(2):Lennox A/C troubleshooting?" , posted Tue 17 Jun 20:32:
Be careful sometimes you don't get a second chance
[this message was edited by marchvac on Tue 17 Jun 20:36] |
| 341
| "Re(1):Lennox A/C troubleshooting?" , posted Fri 13 Jun 17:30
When the fan stops, do have 240V going to the motor or not?
There's no board in the a/c, it's powered right off the contactor. Sounds to me like the motor is overheating and going off on overload.
Take an amp reading, maybe the new motor is turning the wrong
way.
www.hvactechgroup.com
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| | marchvac
| "Re(2):Lennox A/C troubleshooting?" , posted Fri 13 Jun 23:42
Did you replace the motor with a Lennox oem motor. Have you checked the amperage the motor is running at. Has anyone changed the fan blade and install the wrong one.
Be careful sometimes you don't get a second chance
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