Is my Furnace Motor a 1,2, or 3 Speed?

Reply

  #1  
Old 10-18-17, 01:54 PM
Member
Thread Starter
Join Date: Jul 2016
Location: USA
Posts: 63
Received 0 Votes on 0 Posts
Is my Furnace Motor a 1,2, or 3 Speed?



i canít find it how many speeds this is. I would assume 3 because on this board it shows lo Med and hi, but a guy at a local shop thinks itís a one Speed because of the wiring. I have 6 wires out of the motor. Black, orange, red, blue, brown and white, plus the ground.

any idea?

thank you
 
Sponsored Links
  #2  
Old 10-18-17, 02:39 PM
Member
Join Date: Oct 2015
Location: Ct.,USA
Posts: 1,171
Received 25 Votes on 22 Posts
A 3 speed motor usually has 4 wires exiting the motor as the neutral side of each of the 3 windings are connected inside the motor with one neutral wire exiting. There should be a legend on the motor indicating which colors go with each winding (speed) and the connection to line and neutral for a desired rotation. Only 1 winding is energized to run the motor. If you provide the manufacturer and model number, I can check further.
 
  #3  
Old 10-18-17, 04:16 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 52,531
Received 330 Votes on 308 Posts
This is a one wiring method but there are others.
Like beelzebob mentioned... it needs to be confirmed.

red - low
orange - medium low
blue - medium high
black - high
white - neutral
capacitor connected across brown and black
 
  #4  
Old 10-18-17, 07:57 PM
Member
Thread Starter
Join Date: Jul 2016
Location: USA
Posts: 63
Received 0 Votes on 0 Posts
I wish I had a legend.. itís destroyed with age, the my main problem with finding this information out. So on that little panel it says hi, Med hi, Med lo, and lo. This would be a 4 Speed right? Also my transformer has 240v on t so Iím assuming that tells me enough to identify the motor right? 240v 4 Speed motor? Shaft size and diameter of motor are typically the same right?

Thanks you you guys a ton for helping me out.
 
  #5  
Old 10-18-17, 08:47 PM
Member
Thread Starter
Join Date: Jul 2016
Location: USA
Posts: 63
Received 0 Votes on 0 Posts


This is my transformer.
 
  #6  
Old 10-19-17, 07:17 AM
Member
Join Date: Oct 2015
Location: Ct.,USA
Posts: 1,171
Received 25 Votes on 22 Posts
The attached picture of transformer is called a control transformer because itís secondary voltage is low voltage, 24 vac and low power 40 VA. The primary winding of this transformer has connections to operate from 120 or 208 or 240 vac . 120 and 240 are single phase voltages while 208 is a 3 phase voltage. It would be rare to find 3 phase voltage from the utility connected to a residential home. I am assuming this is the control transformer for the furnace utilizing the motor in question. There is no correlation between the AC voltage value supplying the transformer and the motor. The motor (I am assuming single phase) manufacturer designs the motor to operate from a single AC voltage. Some motors can operate from one of two voltages (user selected) and are more expensive. In a hot air distribution system like yours, normally a motor speed is selected for warm weather and a different speed is selected for cold weather by moving the line wire to the desired speed tab on the terminal strip. In your case, you can select one of four speeds for each season or change as often as you desire. What are you trying to accomplish?
 
  #7  
Old 10-19-17, 08:06 AM
Member
Thread Starter
Join Date: Jul 2016
Location: USA
Posts: 63
Received 0 Votes on 0 Posts
Excellent reply, thank you!

If I understand correctly, either a 120v or 240v depending on what is supplied to the transformer? Everything it unconnected (motor and blower housing are removed), so could I kick the breaker back on and just probe one of the speeds and see what the voltage is?
 
  #8  
Old 10-19-17, 09:31 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 52,531
Received 330 Votes on 308 Posts
You need to check what comes directly to the unit. You should know if this is on 120 or 240v.
 
  #9  
Old 10-19-17, 09:54 AM
Member
Thread Starter
Join Date: Jul 2016
Location: USA
Posts: 63
Received 0 Votes on 0 Posts
If I probe at one of the speed terminals where the motor was hooked up. Will this SAFELY. tell me the supply voltage?
 
  #10  
Old 10-19-17, 01:56 PM
Member
Thread Starter
Join Date: Jul 2016
Location: USA
Posts: 63
Received 0 Votes on 0 Posts
Well I probed all the speeds after I turned it on and the only speed that ever had power was the LO speed and it had 123v. The voltage would never change at high speeds right? Just less resistance in the wiring to motor?
 
  #11  
Old 10-19-17, 04:47 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 52,531
Received 330 Votes on 308 Posts
In heating mode.... the fan runs at a slower speed. In A/C mode the fan runs on high.

If you were measuring power from the low speed wire to neutral..... not ground..... then you have a 120v system.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


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