Blower Motor Failure

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I have replaced the blower motor on my Trane Heat Pump system 4 times in as many years. This was a new home system and the first motor went out about 6 months after install. The technician said it was a fluke and since it was under warranty, I was not very concerned. A little over a year latter, it went out again. I called the original installation company and asked why this was happening. They said it was probably due to a dirty air filter. I assured them that this was not the case as the filters are changed regularly. Since now the unit was out of warranty, it would cost me $500 to replace the motor. I replaced it myself with a slightly more powerful motor (from to horse) and that motor lasted almost 2 years. Well now I'm on my 4th motor. The air coming from the registers is very loud; much louder than anyone else's home I've been in. I don't know if this is related or not. What could be going on here? Thanks for any help.
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snipped-for-privacy@comcast.net wrote:

Blower motors should last 10's of years IMHO.
A three-quarter-horse motor seems awfully large for a blower. Maybe you should be using a smaller, rather than larger, motor -- one that wouldn't use as much energy and therefore wouldn't get as hot.
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Im no hvac pro but ive heard improper duct sizing, to small, can stress a blower. It would come under an improper install issue, duct sizing. Get someone else out but first call trane for advise. To low a voltage is bad for AC motors,
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They burn out.
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snipped-for-privacy@comcast.net wrote:

in the motor, which seems unlikely, especially since you've tried more than one model). That can be because they're overloaded, or because they're getting too high a voltage (e.g. due to power surges), or because they're not getting adequate ventilation. I doubt the first, especially since you said you upsized. When you replaced the motor, did you also replace the capacitor? You should have. I'm not familiar enough with the Trane to know about how the motor is ventilated, but upsizing the motor could have worsened the effects of any shortcomings there.
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snipped-for-privacy@comcast.net wrote:

Is the motor has good venting? Not over heating? How did it fail? Mechanical(bearing), electrical(capacitor, burnt winding)? Doesn't seem right.
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I assume the venting is adequate as this is the factory set-up. It is not the cap as this has been replaced each time the motor had been replaced (and a buddy that is an electrical engineer tested it).
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Sorry, to answer the last part of the question, I think is was the windings that burnt as the shaft spins freely and the motor had that unmistakable fried wire smell.
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Can you safely check the ac voltage to the motor while it's running? Is it getting at least 110 V? IF it's lower while running then it's being loaded down. Checking the amps would be useful too.
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I will try this. It is a 220V system so I assume you mean getting at least 210V. But assuming the voltage is OK, would the duct sizing (too small) be a likley culprit?
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I am also thinking undervoltage
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Low air flow is a common cause of blower motor failure. Having talked to many motor manufacturers at seminars, all state heat is the primary cause of failure. With 240 volt system, I assume you have a heat pump.
What is making your motor run hot? If the motor does not have enough air flow to cool it, it will overheat. Primary reasons of low air flow are restrictive air filter (1" pleated or 1" washable electrostatic), dirty air filter, undersized air filter, undersized duct system, registers closed off in rooms you are not using, replacing system with larger system without increasing (replacing) duct system, undersized indoor unit, reusing indoor unit when replacing outdoor unit.
When you replaced the system, did they do a manual J load calculation, or did they use the dreaded 500 sq ft. to the ton rule? Did they measure the air flow from the system with an instrument more accurate than the hand (handometer)? Did they replace the indoor unit? Did they install a new air filter system (They can be restrictive, beware) Did they install new ornamental grilles, especially wood ones (They can be restrictive, beware). Did they put in a bigger system for any reason?
Answers to these questions can help with diagnosis.
One other thing, did anyone measure the amps on the new motor(s) when they were replaced to see if they were using more power than they were rated for?
Stretch
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Just a guess and personal observation...
220 V blower motor..
Hooked up to 110 volt circuit. (or to just 1 leg of 220 V circuit).
Had a well pump like that one time...Well Pump ran fine ... but it would have killed the motor if we hadn't "caught" the problem.
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Well I had what I believe to be a "qualified, licensed technician" go over the system and he could not find a problem. The voltage checked out OK, AMP draw checked out OK, CFM (tested with some sort of electronic sensor) tested out OK. He was puzzled to why the system keeps going through motors. He said the bigger (1/2 to horse) motor was pulling less AMP's than the systems max, so he doesn't feel this is a problem. It was not a dirt problem. It was not a restrictive air problem (at least with the filter).
Question for Roy: Did Mr. Trane test CFM differently and is there a more through test for the duct sizing issue? And what was the final diagnosis of your problem?
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On 29 Mar 2006 07:36:31 -0800, " snipped-for-privacy@comcast.net"

Duct sizing can be an issue, but for now I am letting it go to see how it works out. What he had was better equipment to test out what the elctronic circuits were seeing/doing, as I understand it. But, it was still a real problem to trouble shoot, because it appeared to go away (at least it was quiet, though it was still not operating properly) during the first summer. Also, there was one jumper out of place because the only accurate instructions for connecting in this instance were in the pamphlet for installing the outside unit. (Whenever I have anyone installing anything in my home, I have them give me every piece of paper that comes with it.) On my 16i, which is the only Trane system I have any knowledge on, if one removed the side covers on the air handler one could get RPM by watching the blinking green light (Since it is a fault light, were I building the unit, it would be readable with covers in place). It was obvious the unit was way overspeed, regardless of the dip switch settings. After several attempts, it turned out that the cable connecting the circuit board and the blower/thermostat had a bad lead in it. Cable replaced. Problem went away. Sort of. In the summer with the A/C in use, one cannot tell the sytem is even operating. In the winter the sytem is set to off at night. So in the morning it slowly ramps up as it attempts to reach the desired temp by the desired time. If it gets behind, it blows like hell and is a bit noisy, but still not as noisy as it was when running at max speed before it was fixed. (I also have hot water baseboard heat, and if there is a big differencebetween inside actual/desired, the outside temp is below freezing, or not forecast to rise above 40, I use it to assist, or to take over the entire load. Of interest, I burned 50 gallons of oil from fill in October to fill on Feb, here in VA, and my electric bill went down a bit. from last year) If you want to labor through all that was discussed, the discussion is here: http://www.hvac-talk.com/vbb/showthread.php?threadid 449 along with the previous discussion that led up to it: http://HVAC-Talk.com/vbb/showthread.php?threadidd042 I found a great bunch of guys here. One even called my from TX to discuss it.
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On 26 Mar 2006 08:57:19 -0800, " snipped-for-privacy@comcast.net"

It was a new home but who installed the furnace and duct system? You? A buddy? The building contractor? An unliscened hvac contractor? Spend a few bucks and get your system professionally checked out and repaired properly. Bubba
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Buy new 1/2hp motor, always replace ran cap. ( ~$70 )
Measure ESP. And post it here. Plus your speed settings are: Cooling - high/med/low ? Heating - high/med/low ?
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A sign your ducts being undersized is the cause of your issues is the noise level you note. Its going to happen again and again till you upgrade or find the cause. The original installer is to blame if it is duct sizing. Your larger blower will likely fail sooner.
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Thanks to all for your feedback. You all have been a great help. To answer or clear up some of the questions for you all, this was a new house we had bulit, so as far as the method used to determine duct size, I really have no idea. I did not install nor did a Buddy install the system. It was installed by one of the bigger HVAC contractors in the Indiaianpolis area. I have had dealings with this company before and they do not own up to the fact that there is a design porblem. All of the registers are open and we never close any of them off. I will have my electrical engineering buddy come over and test voltage and amp issues. If any of you are HVAC tech's, what questions should I ask before have have another company check out my problems? My gut tells me that it is a duct sizing issue. All of the failures have been in the winter, while in heat pump mode. The fan is always set to Auto. I have never ran the fan continuously.
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Trane would be your best call and should get you the answer free of charge.
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