Blower Pulses On and Off Every Two Seconds - http://www.hvacmechanic.com/ Forums
Original message
| FSUDAL
 |  "Blower Pulses On and Off Every Two Seconds"
, posted Tue 26 Aug 21:11  
What could cause the blower fan on my residential Bryant Central Heating and Cooling unit to pulsate on and off every two seconds? If I shut off the system the fan seems to operate properly for a while but then unannounced the fault will occur again. Thanking you in advance for your help.
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Replies:
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| fluepipe3
| "Blower pulses on" , posted Wed 27 Aug 19:28
The fan blower capacitor is usually located on the side of the squirrel cage. First shut power off to furnace. Then look for a "tin can" silver attached to the squirrel cage. It will usually have 2 wires attached to it. Make sure the wires were pushed down all the way and not loose.( use insulated pliers, as cap can still hold a charge). If the were, unhook cap fron wires and unscrew cap from cap holder. Is it buldging or deformed? if so replace with one of the same valve. If you have access to capacitor checker you can test it, if not just replace it and see if that fixes the problem, they aren't expensive.
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| | FSUDAL
| "Re(1):Blower pulses on" , posted Fri 29 Aug 09:16
Thank you for your reply. I will take a peek over the weekend to inspect the part.
Ironically, I switched the fan setting on the programable thermostat upstairs from AUTO to ON (this causes the fan to run continuously on the low setting and then kick on high during cooling). The unit has been running fine ever since.
I wonder if the thermostat could potentially be the problem or if it may just be masking the capacitor problem since the blower does not need to start from a dead stop?
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| Jojo98
| "Re(1):Blower Pulses On and Off Every Two Seco" , posted Tue 26 Aug 22:18
Sounds like a run capacitor.
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| | FSUDAL
| "Re(2):Blower Pulses On and Off Every Two Seco" , posted Wed 27 Aug 09:10
Thank you for your timely response. Although I was an electroncis tech in the USMC many years ago I am not an HVAC tech. How can I check to see if this is the problem and fix it?
I forgot to mention in my original post that the amber light is on and does not blink. I think this means no error code is currently being reported?
Also, are there any good resorces/books for someone like me to tap into--with pictures? :)
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| | fluepipe3
| "Blower pulses on" , posted Wed 27 Aug 19:30
What is the make and model number of your unit?
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| | FSUDAL
| "Re(1):Blower pulses on" , posted Fri 29 Aug 09:11
It is a Bryant 90i which cools and heats. I'm not sure if that is the actual model number or not. Let me know if that helps. Thanks again for sharing your knowledge!
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| | FSUDAL
| "Re(1):picture" , posted Sun 31 Aug 12:01
quote:
http://www1.snapfish.com/slideshow/AlbumID=245833489/PictureID=5687705966/a=143047178_143047178/t_=143047178
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Nice! Thank you for that. I looked around but could not find the run capacitor. I tried to attach two pictures in hopes that you help me find it (not sure it the pictures will come up for you. It doesn't seem like there is an easy way to share pictures on this site). The wires would suggest that it may be inside the motor?
Also, I switched the fan setting on the programmable thermostat upstairs from AUTO to ON (this causes the fan to run continuously on the low setting and then kick on high during cooling). The unit has been running fine ever since. I wonder if the thermostat could potentially be the problem or if it may just be masking the capacitor problem since the blower does not need to start from a dead stop?
Thanks again!
Two pics via link;
http://www1.snapfish.com/slideshow/AlbumID=245833489/PictureID=5687705966/a=143047178_143047178/t_=143047178
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