blower fan won't run with buzzing sound

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  #1  
Old 04-21-11, 05:00 PM
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blower fan won't run with buzzing sound

In the middle of night, after running a/c about 3 hrs, I noticed fan was not running and started hearing buzzing sound. Mine is bryant, 9.5 years old, split system. Outside unit was running and I could hear compressor was running. As fan won't run with or without a/c at all with the buzzing sound,

I pulled out the motor from the cage and was going to replace capacitor first to see what happens. ( I don't know how to check if a capacitor or not but it's just ten bucks). Before I replace, I turned it on just to see what's going on and the motor ran without an issue.

However, after I put the motor back in, and put the whole thing back thinking the motor was seized somehow, it ran about a second and got stuck with buzzing sound again. The shaft turns quite freely with a hand

Will it be a weak capacitor? or motor is failing?
Can anybody suggest what to do next?

I appreciate any help in advance
 
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  #2  
Old 04-21-11, 05:19 PM
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Usually if the motor spins freely, it is the capacitor problem. However, the capacitor is only used to start the motor. If the motor stops while running then id replace the motor. But I would replace the capacitor first either way.
 
  #3  
Old 04-22-11, 06:53 AM
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One other possibility is a bad blower relay.

Is the sound actually from the motor? Is the sound a "buzz" (obnoxious) or more like a gentle "hum"?

Bad Relays can buzz loudly. Motors will usually hum quietly.
 
  #4  
Old 04-22-11, 09:45 AM
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If the motor ran OK ouside the cage(?), then the problem is your cage or the way you put it in.
 
  #5  
Old 04-22-11, 12:40 PM
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It may be time to remove and bench test the entire blower. Power it directly from the line and see what happens.

As mentioned, It could be an interference problem. It could be a control problem.

Are the motor bearings good. Does the shaft have play from side to side?
 
  #6  
Old 04-24-11, 12:19 AM
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i changed capacitor first to see what happens. The same result occurs that the blower won't run. So I took out a motor and tried several times. The motor seems to seize up half of the times. I believe the buzzing sound (big humming sound) seems to come from the motor. I checked with a hvac shop through a friend and they don't have it and will have it by Monday.

I didn't know it could be a relay. Dang. I already ordered the motor through a friend who has access to hvac supplies shop. However, the control seems okay to me because the motor gets powered each time i tried.

Is there any temporary solution I can get this motor to run? it's 83 here in the house.
 
  #7  
Old 04-24-11, 12:52 PM
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The motor seems to seize up half of the times
Probably the motor.

I very well could be bad bearings. Grab the motor shaft. Does it have play from side to side?
 
  #8  
Old 04-24-11, 01:41 PM
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i think it does. I am not sure if armatures is shot.
 
  #9  
Old 05-23-11, 02:26 AM
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Arrow

I also have a similar problem.
The blower is not working with cooling on my Lennox G26Q3-50-2 gas furnace. The blower works fine with heating but it failed to work with cooling. Checked the control board and all connections look OK. I have given it enough time after the compressor started so it doesn't look like a normal delay. Haven't done any voltage test yet. The thermostat is Honeywell 5-2 and the wiring is 4-wire heating and cooling with jumper between heating and cooling power supply.

I look forward to your advice.

Thanks
 
  #10  
Old 05-23-11, 07:17 AM
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9 times out of 10 motor is shot, jif you have voltage to your motor and proper microfarads at your capacitor change the motor. good luck
 
  #11  
Old 05-23-11, 08:33 AM
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Thank you for the quick response. just couple of Qs for clarification: if the blower (supply air blower, not combustion air blower) is working with heating could it still be the motor problem? From my readings it looks like the blower is controlled by the furnace fan control circuitry system during heating. If that is the case, does this circuitry use a different capacitor and motor than the thermostat would use to control the blower during cooling?
By the way, I also tried the continuous fan On mode without the heating and or cooling but it still doesn't work. So what is the proper microfarad I should get on the capacitor during testing? Let me also know if there is any other thing that I need to check.

Thanks!
 
  #12  
Old 05-23-11, 11:00 AM
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either your high speed {air cond.} is out or the fan relay is faulty, could possiblyu be t-stat also.
 
  #13  
Old 05-23-11, 11:03 AM
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because motor is humming yea bad motor mor than likely, if it has volts going to it and its humming time for a new motor.
 
  #14  
Old 05-24-11, 06:36 PM
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Thanks again for the advise. Just a small clarification: I actually don't hear any buzzing or humming sound. The only sound in the unit that I can hear is a faint 'shshsh' sound which I guess is coming from the compressor. Re the t-stat, it is about three years old and no sign of damage; both the heating and cooling relays are working fine. Initially the AC (outdoor unit) wasn't starting. After I found a broken connection of the cooling relay on the control board the AC starts and runs fine. So the only problem is the fan not working with the cooling. I will try to do the power test once I have my multimeter.
Thanks
 
  #15  
Old 05-25-11, 05:48 AM
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once again if you have 120 volts to the inside blower motor and it is not spinning or rotating you need a new motor. If there is not any voltage than you have either a faulty t stat or relay which in your case means a new circuit board wich again is not cheap.
 
  #16  
Old 09-19-13, 12:26 PM
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Similar Problem - Blower Motor Won't Start

Lennox G12Q4E-120-12 ... (testing as the heating season begins)
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Blower intermittently refuses to start in heating mode; it'll usually start up on the first cycle after being off for a long time, but then not on subsequent heating demands ... just humming and heating itself up until tripping its thermal overload. Measured voltage to motor does not load down to less than 118vac when it's trying to start up.
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This happens when wired for low and medium-low speeds. Apparently always starts successfully when wired connected to the medium-high speed.
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A/C and "Fan" modes work fine.
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Repairman tried replacing capacitor and that seemed to fix the problem, but it reoccurred after he'd left (not sure whether or not the replacement capacitor was new or just something off his truck.) The fan turns freely, and the repairman did make sure that the motor was properly lubricated. Motor is reasonably clean and its shaft does not seem to have any play in it.
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i.e.: Apparently not enough oomph to start up when wired for either of the low speed modes. Try another capacitor? ... or possibly a troubled motor?
 
  #17  
Old 09-19-13, 03:55 PM
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First of all, I would call the technician back that worked on your system and tell him the situation. He was paid to properly diagnose the problem and install the correct part to properly operate. How long after he left did the problem re-occur?Did the technician check the incoming voltage to the control board and outgoing voltage to the fan motor. It could be a defective capacitor right out of the box. Did the technician verify it was within specs before he installed it? Need to make sure the grounds are good. Could be a control board issue.
 
  #18  
Old 09-19-13, 08:20 PM
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Fan Won't Start in Heating Mode

Yes, he knew it was an iffy situation, since the malfunction is somewhat intermittent, and he didn't leave with the intention that the problem had been positively diagnosed and fixed. It failed again that same afternoon, which came as no surprise to either him or me. He'll be back tomorrow.
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As mentioned in my original note, when the motor stalls on start-up, the voltage connected to it isn't loaded down to less than 118vac, which should be sufficient. Giving the fan a little spin-up help by hand is enough to get it going when the motor is just sitting there humming. The problem occurs when the motor is connected for Low or Medium-Low speed in the heating mode. When connected for Medium-High operation in the heating mode, it works normally.

Thanks for your input.
 
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