Trane Attic Air Handler Not Coming On


  #1  
Old 01-10-10, 01:02 PM
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Arrow Trane Attic Air Handler Not Coming On

I have Trane system in my home.... Downstairs is natural gas fired and upstairs is handled by a heat pump and air handler in the attic. Well... I woke up this morning to 55 degrees upstairs. Downstars is fine. I went up in the attic to check the air handler. When heat is called for the handler just hums. I turned off the breaker as well as pulling out the one on the unit. I pull the side cabinet off after taking out about 7 screws. I then turned everything back on.... The whole thing starts humming and the motor starts turning VERY slowly. I was afraid if this was left to keep going... I would burn up the motor... So I turned everything back off. In my reading I noticed that capacitors are usually the culprit here.... I have a GE 97F9001 - 370VAC capacitor on the side. It has the normal oxidation on the leads but no noticable bulging as some of the examples I have seen on the web. The system is 8 years old. When it was 2 years old they had to come out to replace some sort of relay in the summer as the air handler had stopped then too. No problems since then.... I change my filters regularly and had an AC guy come out and check the outside this past year as I thought it may be low on coolant since it was taking forever to cool the inside of the house. (It wasn't low on coolant... Just REAL hot outside!) He added a "boost capacitor" to the outer unit explaining that as they get older they need a little extra boost to get them going. (The unit had kicked my breaker once before this was added.)

So anyway... Back to my current issue... The upstairs air handler hums loudly and the motor starts to turn slowly but never gets up to speed... Any ideas here? Any advice would be greatly appreciated.

Thanks,

Rick
 
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Old 01-10-10, 01:25 PM
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If the blower wheel spins freely with power removed it is probably the capacitor. You can measure the capacitor with a $30 meter available at Sears.



A meter will display CAP, uF, or have a polarized capacitor symbol if it measures capacitance.



Small run capacitors rarely have a noticable swelling, like dual caps, when they fail.
 
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Old 01-10-10, 01:34 PM
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Yeah... But I think the capcitor itself is under $20... I'm all for having more tools... But I already have 3-4 multi-meters... Unfortunately... None measure capacitors.

I thought there was a way to do it with a regular DVM...

I'll just buy a new capacitor if I can find one around here.... But if someone else has experience with this and thinks it may be something else... Please let me know.

Like I said... It starts humming LOUDLY and the fan starts to move but barely. With the power off... You can spin the motor freely.... No problems there. It isn't seized.
 

Last edited by Rick Kirby; 01-10-10 at 02:38 PM.
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Old 01-12-10, 10:25 AM
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Well... I went to the local HVAC supply and paid a whopping $2.32 for a new capacitor. I installed it and the motor STILL made that humming noise but then started to blow. It doesn't seem to blow with the force I remember it blowing however. By the time I instaled the capacitor... It was 63 degrees upstairs. The Uax Heat kicked on and it eventually (Over about an hour)got it up to 68. I noticed that the AuxHeat turned off when it got to about 66F.

So I am pleased with myself... Waiting for my wife to get home a few hours later... She goes upstairs and it is back down to 65 and the thermistat is showing that nothing is going on... (No Heat)

So much for the bad capacitor. Am I correct in assuming that the only other thing that could be would be the blower motor itself? About a week before this my wife could swear she smelled a "Burning Smell" upstairs.... I couldn't smell it but that is no suprise. Could it have been this motor going bad... Struggling to start up and overheating?

It looks like a new blower motor is going to cost a min of $400-$500. (Just for the part!) I'm thinking for that kind of money I should probably just call someone out to take a look at it even if it is to confirm my suspicions.

Any thoughts?
 
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Old 01-12-10, 06:10 PM
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Reading you initial post the motor was my first thought. You wanted to try a capacitor, eh 10% maybe but you will need one for the new motor anyway.

So, now you know it is infact the motor. $400 - $500? If you are used to that, find a new contractor.

Take the motor out and bring it to a local HVAC supply house to match it to a new one. Make sure the new $2 cap you have will work for the new motor. Never change a motor or compressor without changing the cap.

Might be a little difficult getting the old motor out, but it is a DIY. You will need to remove the entire blower housing to do this and it WILL be a pain in the ass. Word to the wise....
 
 

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