Furnace Blower Works, but No Air Flow


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Old 12-15-13, 02:14 PM
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Furnace Blower Works, but No Air Flow

We have an old Honeywell furnace (like 35 years old - just furnace - no ac). When the thermostat is turned on, the furnace burners kick on (I see the flames)... a few minutes later, the blower motor turns on (just replaced it - I see and hear it spin)... but NO (very very slight) air flow through vents (In fact, the air flow is so slight, i'm not sure if it just isn't hot air rising naturally). Since we just replaced the blower motor, we tried changing its pull direction by switching the leads to the motor, but still no air flow. What to do?
 
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Old 12-15-13, 02:26 PM
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Yep, it sounds like you must reverse the motor rotation. Did you buy a universal motor that allows this?
Post the make and model of your new motor.
 
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Old 12-15-13, 02:28 PM
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Well... when I purchased the motor, they told me that in order to change the direction, I needed to change the leads to the motor. I've done that, but still nothing...
 
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Old 12-15-13, 02:32 PM
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Since you changed the motor, that means you must have swapped over the squirrel cage fan. Did you inadvertently put it on wrong? Seems like the only explanation, if the motor is spinning up to full speed.

As to changing the direction by swapping leads...I don't think it works that way on an AC motor unless the motor is reversible, and then you use a different lead, not just swapping the connections. (I think!)

Check the old motor nameplate vs the new. Make sure the rotation (CW or CCW) is the same.
 
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Old 12-15-13, 02:38 PM
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Changing L1 and L2 will not reverse rotation. Many motors have 2 orange and 2 purple wires that must be crossed to reverse rotation. Some motors have a white plug that must be reversed to change the rotation.

Post the make and model of your motor so that we can look this up for you.
 
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Old 12-15-13, 02:56 PM
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Motor Model Nol

Ok.
The motor is a Century AC Motor...
S# 316P769
SER 29113J2
HP 1/3
RPM 1735

[EDITED]
Sorry I'm so bad at responding completely and correctly

stock number GF2034
 
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Old 12-15-13, 03:50 PM
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The motor is a Century AC Motor...
S# 316P769
SER 29113J2
HP 1/3
RPM 1735

stock number GF2034
 
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Old 12-15-13, 04:40 PM
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Looks like you need to interchange the red wire on 4 and the black wire on 2 to reverse the rotation.

 
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Old 12-15-13, 10:12 PM
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You're Awesome: One More

Okay!!!
Thank you for being awesome and going out of the way (with pics and all) to show me what to do!!!

The direction changed worked... BUT, now the blower is continually going on and off... what's causing that? What do I need to do to fix it??

Again, thank you so much!
 
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Old 12-15-13, 10:35 PM
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Did you put your incoming black wire on L1 and Neutral on L2 as shown in the diagram?

Is the blower panel on?

Does the gas continue to burn while the blower short cycles?
Does your old motor have the same amp rating as the new motor?
Does it have the same voltage and RPM?
 
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Old 12-15-13, 10:42 PM
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I believe that I simply switched then red and black wires.
Yes, the blower panel is on.
Yes, the burners stay on while the blower short cycles.
 
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Old 12-15-13, 10:46 PM
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Since we just replaced the blower motor, we tried changing its pull direction by switching the leads to the motor, but still no air flow. What to do?

Did you ever put the wires back where they belong?
Black goes to L1 and White on L2.
 
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Old 12-15-13, 10:47 PM
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Did you put your incoming black wire on L1 and Neutral on L2 as shown in the diagram?

Is the blower panel on? Yes

Does the gas continue to burn while the blower short cycles? Yes
Does your old motor have the same amp rating as the new motor? I have no idea
Does it have the same voltage and RPM? I have no idea
 
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Old 12-15-13, 10:50 PM
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The replacement motor must match the specs of the original motor.
If the old motor was 240 volt and the replacement is 120 volt it will not work.
If the old motor was 1 horsepower and the new motor is 1/3 horsepower it will not work.

What I suspect the problem to be...
If the old motor was rated at 9 amps and the new motor is 5.9 amps it will not work.
 
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Old 12-15-13, 10:52 PM
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I'm pretty sure that I did BUT I will go check...

How can I tell which is L1 and/or L2 ???? (I think I know, but I just want to be sure if possible)...
 
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Old 12-15-13, 10:54 PM
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I read it using a small flashlight.
 
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Old 12-15-13, 10:56 PM
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Well... this IS problematic. How can I tell what motor I will need. They kept the old motor and I'm not sure I can get it back... not sure what they do with them.

Why did it not turn on and off before??

PS - can I leave it on for a few days until I get the replacement? ... Just to have heat?
 
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Old 12-15-13, 10:58 PM
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It did not have a load on it before.
You can lower the amperage by opening the pulley with belt drive motors.

 
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Old 12-15-13, 11:05 PM
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You don't know how much your help and patience has meant to me. Thank you again.

I'm going to see if I can research "how to lower the amperage on a belt drive motor by opening the pulley." I'll probably be back.

[edited]
Thanks for the research... i didn't see it till i had already posted this.
 
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Old 12-15-13, 11:35 PM
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Here's what I can read from the metal tag on the furnace... btw.... the furnace is a Luxaire furnace...

120 v
7 amps
 
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Old 12-16-13, 01:00 AM
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Blower short cycles

Prior to changing the direction of the motor...
1.) we would call for heat
2.) the burners would kick on
3.) the blower would kick on
4.) the burners would go out and the blower would just run

Now that we've changed the direction of the motor (so that it is forcing air up the registers)...
1.) we call for heat
2.) the burners kick on
3.) the blower kicks on
4.) the burnes stays on
5.) the blower cycle on and off
6.) Once call for heat tempture is met the burners go off


I don't have specs for the old motor (we left it at the store where we purchased the new motor... not sure what they edid with it). BUT, the rating for the electrical for the furnace is 120v 7amps. So, I would guess that the old motor was 120v 7amps (as it was original motor).

The motor we have now is 120v 5.9amps...

Houston204 suggests that the problem is due to the non-exact motor replacement (which makes absolute sense to me). BUT, I don't fully understand the possible solutions.

One solution was to lower the amperage (and thus, I believe, the fan speed) by opening the pulley. I guess, what I don't understand though, is that if the older motor was at 7amps and this one is at 5.9, then it seems like it would already be lower... I'm missing something big here.

I guess, I'm just not sure what should be my next move as far as the motor. Can I make adjustments that will fix this? Or am I forced to get the 7 amp motor?

Or, is there something else...

Thank you
 
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Old 12-16-13, 05:29 AM
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If you have a seven amp load and install a 6 amp motor it will still pull 7 amps.
You can reduce the load by opening the pulley 2 turns.
You would need to adjust belt tension afterward.
You want 1 inch of belt play. Do not over tighten.

The inlet and outlet temperatures should be measured 2 feet from the furnace to verify that we are not exceeding the rated heat rise listed on the furnace nomenclature.
 
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Old 12-16-13, 09:56 AM
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Thank you Houston204!

I think it's FIXED.
 
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Old 12-16-13, 05:10 PM
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That is great news.
Thanks for posting back with your results.
 
 

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