Blower motor problem


  #1  
Old 07-02-14, 06:53 AM
J
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
Blower motor problem

I wasn't sure where to post this but it's 90 degrees out so I thought the A/C forum would be appropriate.

About a month ago I started to here some rumbling from the blower motor. when the A/C turned on. My central system is more then 20 years old and has been trouble free(although expensive) for the 8 years I have lived in the home.
I noticed it was a bit tough to spin the fan in the housing. At that point I removed the motor to take a closer look...

This electric motor has oiling holes. No bearings and not something I have ever seen before. The company that services the unit never mentioned it and I for sure haven't oil it. After taking the motor apart I was able to clean the shaft off(there was a sticky oil residue). Mostly on the part of the shaft that extends out of the motor end plate. That would be the side that's almost impossible to oil without removing the motor. After a good cleaning and some fresh 30 oil everything is smooth again. It spun freely and no play between shaft and sleeve. I thought I dodged a bullet but 2 weeks later it started to get hard to spin again. Repeat

Here are my questions:
Is straight 30W oil correct?
Why would the oil gum up again?
How does this system supply fresh oil to the shaft and sleeve?
There is some material in there designed to hold the oil but it doesn't touch the area that needs oil. Is that my problem?
 
  #2  
Old 07-02-14, 07:04 AM
J
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
While I'm here and suspecting I will need a replacement soon...
What would be appropriate replacement for this? I'm not an easy time with the cross reference. Maybe because of the age.
 
  #3  
Old 07-02-14, 08:19 AM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,521
Received 94 Upvotes on 87 Posts
It is just a standard 3 speed 1/3 horsepower 115 volt 7 amp blower motor. I would be sure the replacement does not have oil ports and is at least 7 amps.

Get a new capacitor for the new motor.
 
  #4  
Old 07-02-14, 09:05 AM
HVAC RETIRED's Avatar
Member
Join Date: May 2008
Location: Wisconsin USA
Posts: 664
Upvotes: 0
Received 0 Upvotes on 0 Posts
An A/C Supply Outlet will cross-reference the motor, it needs to be as identical as possible & be a 48Y frame motor. Also, what Houston204 stated...
 
  #6  
Old 07-02-14, 10:42 AM
J
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks for the quick answers. Looks like I joined the right forum.

Is this old motor not worth discussing? Even though the final resolution will be replacement, I'm curious how this oiling mechanism is supposed to work.
 
  #7  
Old 07-02-14, 10:50 AM
J
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks again for the links.
About the specs:
The number of speeds should not matter correct. My system is just on or off. I guess I would wire for high speed?
The 7amp on my old motor is what the motor draws? The new motor could be lower?
 
  #8  
Old 07-02-14, 10:57 AM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,521
Received 94 Upvotes on 87 Posts
The load creates the amp draw.
If your old motor draws 6.9 amps and you install a 5 amp motor it will draw 6.9 amps and drop out.

Most gas furnaces use a lower speed for heating than for cooling.
 
  #9  
Old 07-02-14, 11:04 AM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 19,281
Received 6 Upvotes on 6 Posts
Speeds may matter. Is this only for A/C? Do you know what speed it was running at before? Probably high, yes, but not always.
 
  #10  
Old 07-02-14, 12:12 PM
J
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
It's an oil furnace.. I'll order a new one sometime soon. I'm sure I will need to confirm wiring after I get it. Maybe this picture will help.
 
  #11  
Old 07-02-14, 02:25 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,521
Received 94 Upvotes on 87 Posts
Looks like medium and low speed are in use.
 
  #12  
Old 07-02-14, 05:11 PM
J
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
How are the two speeds used. I haven't heard the fan speed change. Does heat or A/C use a different speed?
Do the speed have a big effect on register air temperature?
 
  #13  
Old 07-02-14, 05:45 PM
S
Member
Join Date: Feb 2014
Location: USA
Posts: 1,771
Received 0 Upvotes on 0 Posts
High is for cooling and medium speed is for heat. Yes the speed is very important.
 
  #14  
Old 07-02-14, 07:37 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,521
Received 94 Upvotes on 87 Posts
I am not an oil burner tech Gunguy and PJ help with that type of furnace but I have seen some older models have a fan limit.

This drawing illustrates how 2 speeds are used with an old gas furnace that used a fan limit...

Name:  furnacestandingpilot.jpg
Views: 6617
Size:  20.3 KB

Newer furnaces use a control board.

Looks like your black is capped and you are using blue and red speeds.
 
  #15  
Old 07-02-14, 09:10 PM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 19,281
Received 6 Upvotes on 6 Posts
Gunguy and PJ help with that type of furnace
Houston is confusing me with one of the East coast guys, I think. I know the electrical part of furnaces and A/C to some extent, but that's about it.
 
  #16  
Old 07-03-14, 06:41 AM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: United States
Posts: 9,871
Received 185 Upvotes on 166 Posts
Is this old motor not worth discussing? Even though the final resolution will be replacement, I'm curious how this oiling mechanism is supposed to work.
That older Emerson motor has powdered iron sleeve bearings and although it has oil ports, relubricating those motors is not nomally required during the life of your furnace. Powdered iron is porous and allows oil to flow slowly through it to the bearing surface. Emerson sold their motor business to Nidec several years ago, but a direct replacement is still available from Nidec and several other manufacturers. Take the motor to a HVAC supply house and they'll have a replacement.

Home

The motor speeds are critical so you need to know what speeds your motor was connected for. Speaking generally because most air handler/furnaces are located under the house in a basement, cool air is harder to move up into the house than warm air and generally requires the A-C be connected to run one speed faster than the heating speed.
 
  #17  
Old 07-03-14, 07:13 AM
HVAC RETIRED's Avatar
Member
Join Date: May 2008
Location: Wisconsin USA
Posts: 664
Upvotes: 0
Received 0 Upvotes on 0 Posts
The motor speeds are critical so you need to know what speeds your motor was connected for. Speaking generally because most air handler/furnaces are located under the house in a basement, cool air is harder to move up into the house than warm air and generally requires the A-C be connected to run one speed faster than the heating speed.
Exceptions:
In many northern climates, when the A-C is sized right & heating is still oversized, the heating blower speed can be higher than the cooling speed in order to keep the furnace temp-rise within mfg'ers specs.

In other more moderate climates cooling usually requires the higher blower speed.
 
  #18  
Old 07-03-14, 07:18 AM
J
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks for explanation Joe. Makes some sense to me now. I still cant figure out why the oil would be gumming up in a couple weeks time. Maybe it's not just oil but a fine iron powder metal combination. It also appears I should be using a 20W oil instead of 30. Maybe its too thick. In any case thanks for the info. I just like to know.

Regarding the replacement.. I looked at the links you gave me PJ. Those sites don't list amp rating and every motor I have looked at seem to be in the 5 amp range. My local supplier cant seem to cross reference that number either.
 
  #19  
Old 07-03-14, 12:03 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: United States
Posts: 9,871
Received 185 Upvotes on 166 Posts
Regarding the replacement.. I looked at the links you gave me PJ. Those sites don't list amp rating and every motor I have looked at seem to be in the 5 amp range.
Your motor is something over 20 years old. The newer motors are higher efficiency than the old one. I wouldn't expect to find a replacement that drew the full 7 amps. As long as HP, voltage, frame size and speeds are the same, it should work fine.
 
  #20  
Old 07-03-14, 01:20 PM
J
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
That's what I was thinking.
 
  #21  
Old 07-03-14, 01:42 PM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 19,281
Received 6 Upvotes on 6 Posts
I still cant figure out why the oil would be gumming up in a couple weeks time. Maybe it's not just oil but a fine iron powder metal combination.
Worn bushings (what I call them) get hotter. Old oil or no oil caused them to run dry for a while, then wear. Cleaning and adding oil helped, but the wear caused the oil to overheat and more wear.

Same thing as old cheap desk fans or wheel bearings. Take 'em apart, clean 'em up, re-lube...wow..works great...for a while.
 
  #22  
Old 07-03-14, 03:20 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,521
Received 94 Upvotes on 87 Posts
I have replaced 20 year old motors with new blower motors that pulled more than the rated amperage this year. You are not using high speed so this may not be an issue but I would check the running amperage on the new motor and expect the amp draw to be similar to the old one.

I'd go up to half horsepower before using a 5 amp to replace a 7 amp motor but it is your decision and I do wish you the best of luck with this replacement.
 
  #23  
Old 07-07-14, 09:59 AM
J
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
So the new motor and capacitor is in transit. I was looking at the wiring diagram ahead of its arrival and had a few questions. It's an inexpensive AO Smith DL1036

Electric Motors-HVAC | 5" Diameter 48 Frame | Century DL1036, Direct Drive Blower Motor - 1075 RPM 115 Volts | B185903 - GlobalIndustrial.com



I should be able to match the speeds up. They appear to be the standard colors.
Can I assume the new brown/white would go where my old white is?
Where does this new yellow go?

Rotation is determined by looking at it from the shaft end?
 
  #24  
Old 07-07-14, 10:51 AM
S
Member
Join Date: Feb 2014
Location: USA
Posts: 1,771
Received 0 Upvotes on 0 Posts
Your new motor will wire up differently. The new cap will only have two wires on it ( Brown and brown/white). The Yellow will be your neutral, which will wire nut to the ( looks like you have 2 blacks and a blue coming in to the box) black wire that is going to the cap.
You bought a reversible motor is that will be easy to change.
 
  #25  
Old 07-07-14, 11:33 AM
J
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
So I am going to cut the spade off the black on the cap and connect to yellow. Thank You.
 
  #26  
Old 07-11-14, 12:29 PM
J
Member
Thread Starter
Join Date: Jul 2014
Location: USA
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
Motor is in and purring. I didn't all the noise the old motor was pushing through the ductwork. Other then one wire it really was just a R/R procedure.

I just wanted to post one more time to say Thank You to all willing to help me out. A site like this with correct, helpful and quick answers is rare. I am glad to have found it.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: