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jerrid · Aug 27, 2006, 11:57 AM

Hi. Yesterday the blower motor for my central air did not initially come on when tripped by the thermostat. It did come on in a subdued fashion a few minutes later. When I turned it off after a minute or so, the motor shaft was quite hot and there was an electrical smell near the unit.

The appliance parts store found that the capacitor attached to the blower unit was faulty and suggested that I just try changing it instead of putting in a new motor. I replaced the capacitor and the blower now seems fine; it turns off and on each time and after running for an hour the motor shaft stayed cool. I was happy as the capacitor costs a lot less than a new blower motor.

However, a friend, the local handyman who works on air conditioners, said that I still need to replace the motor because the capacitor I replaced is a run capacitor, not a start capacitor, so it could not have caused the motor problem I had observed. Further, he said the blower motor will probably fail again soon and this could result in damage to the central air unit (outside the house).
Does anyone know who's right? Can I keep the old motor or does it have to be replaced? The blower is part of the electric heating unit. Thanks!

rickdb1 · Aug 29, 2006, 05:18 PM

A defective run capacitor certainly can cause the motor to overheat and will cause exactly the symptoms you had. Nonsense to replace the motor when it's working properly... If every blower motor that went out caused damage to the condensing unit, I'd be a lot busier...

letmetellu · Aug 29, 2006, 09:44 PM

If the old capacitor and the new capacitor were both silver and if the ratings were the same, something like 5uf 370, you should be OK. Now the numbers don't have to match what I put above, just so the ones on the old and new capacitors match.

jgj6331 · Aug 30, 2006, 09:06 AM

If the new capacitor fixes the problem - GREAT - but if the motor has been overheated and you noticed a strong "electrical smell", there may be some damage to the motor. Make sure it has been adequately lubricated to relieve any friction. Check the motor with a clamp-on ammeter during start up and while running to test for abnormal current draw. Make sure it is properly grounded. Lastly, watch it closely - like your handyman friend suggested, a failed motor could lead to a tragic chain of events ruining your AC ($$$). If your AC is going to be unattended for any extended length of time, - cut it off.

jerrid · Aug 30, 2006, 11:30 AM

Thanks all three for your insights.

On a related matter, I was told that the other motor (on the outside unit - the condenser fan motor I think) should have two holes for oiling, each with a black plug.

I found one such hole but could not find the second. There are two other holes on that end of the motor but neither has a black plug and both seem to go down just 1/4 inch before I hit what sound like metal (when I poked around with an awl - gently)

Could one of these somehow be the second oiling hole?

Thanks,

Jerrid

jgj6331 · Aug 30, 2006, 12:37 PM

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They should be at each endplate and should lead all the way to the bearings... See attachment,, This is for the indoor blower fan - the outside fan is sealed to protect it from the elements and may not have lubrication ports - and thus the origin of the fabled "Permanently Lubricated Motor"...

bernie66191x1 · Sep 3, 2006, 01:27 PM

I am having a plumbing problem which requires that I remove a portion of the large fibre board (ductboard) A/C return duct. I plan to cut into the section to be removed and then replace that section when the repair is completed. How do I reattach the ductboard so that it stays together with the parts that I don't remove?
Thank you for your assistance.
Bernie

jgj6331 · Sep 3, 2006, 01:49 PM

Bernie,
You need to start a new thread here ("Ask about heating and air conditioning" - see top of this page) - otherwise people might miss your question. But, to answer your question here - you can buy metal clips for that purpose at the hardware store. They are commonly used for plywood but should work here. They look like 2 "U"s end to end. After you get it clipped back in, seal the seams with aluminum duct tape. Alternatively, you can span the hole inside with a couple of 1x2" pine furring strips - use dry wall screws to attach the ends to each side of the hole, then replace the piece you removed and attach it to the furring strips with a few more screws - then cover the seams with aluminum duct tape to make it air tight.

dvanilla · Jan 8, 2010, 10:28 AM

Can anyone tell me if the capacitor, transformer and air handler unit how does it relates to each other. I was told my transformer was out, then I was told I have no transformer I have a air handler unit. My ac and fan on was working, my heat refused to come on. Upon diagnois my thermostat check and I was told it was bad. I replaced the thermostat and the same company who said the thermostat was bad came out and checked it now nothing works. Now there saying its my transfomer, At this time I'm really confused and don't won't to spend anymore money. My appointment with the company on yesterday, I expected them to come out last night and found out the supervisor said, "he wasn't sending anyone else out" here it was my son, pets and I slept in a cold house with only a small electric heater and open oven to stay warm.

cdeaton · Apr 14, 2011, 05:31 PM

Fan on outside central air unit not running. Guy came yesterday and changed capicitor. It worked and fam was blowing. Came home from work today - fan not spinning. What could be wrong? Should I call the air guy back? Why would it work and then quit working again so soon?

Help!

jgj6331 · Apr 14, 2011, 06:02 PM

Could be a bad motor that's overheating - or the bearing may be worn and possibly seized - much less likely would be a bad replacement capacitor. Check and make sure the circuit breaker is not thrown. Yep - you'll likely have to call the guy back...