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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: RE: Why do you think I recommended twisting the ground around the ic"s? posted by jking67 on January 10, 2008 at 14:19:43:
Call a heating/cooling company and have them check out the motor on your furnace. If the furnace squirrel cage fan is belt driven the motor has two windings. A Start winding, ( Gives the motor shaft direction and starting torque), and the second winding run.
The centrifugal switch is in the closed position with no power applied to the motor. When the thermostat calls for heat the burner comes on. When the heat reaches a preset temperature on the fan/limit switch a contact closes and completes the circuit for the fan motor to start. (Is this switching action causing the click you are hearing? The fan/limit switch contact?) At this point both the start winding and run winding are energized.The fan motor's start winding causes the motor to very quickly start turning, (A start capacitor is used for a quick starting torque). After a preset RPM roting speed, of the motor, the centrifugal switch opens dropping out the start winding. (Is this when your here the click from your speakers?).
The centrifugal switch is mounted on the back side of the motor shaft just inside the end-bell. Oil, dust, even lint, can get into the contacts of the switch.
========================Furnaces with direct drive fan/motor do not use motors with centrifugal switches...
With out pulling any front covers off the furnace you can tell which type you have. Turn the thermostat up to call for heat. Go stand in front of the furnace. Wait and listen for the fan motor to start. If the motor has a separate start winding you will here the fan come up to speed very quickly. Direct drive motors a lot slower coming up to speed.
If you do the test have someone also listening to your audio system. For communication use a cell phone and your land line phone. Discuss first what the role of each of you will be for the test.
The person at the furnace will listen for the very instant the motor first starts and reports that instant to the other person. (was the click heard from the contact closing on the fan/limit switch?)
If the fan/motor is belt drive almost instantly after the motor starts, a couple of seconds at the most, the centrifugal switch will open dropping out the start winding. Was the click heard at this point?
My gut feeling, if the the fan/motor is the centrifugal fan switch type, this is the problem.
Edits: 01/11/08 01/11/08
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Follow Ups
- Al was on the right track with his post. - jea48 09:14:28 01/11/08 (9)
- Line noise and then agian. - jking67 13:57:01 01/11/08 (8)
- Does the motor have an AC capacitor across it? - jea48 17:56:29 01/11/08 (1)
- RE: Does the motor have an AC capacitor across it? - jking67 05:35:37 01/12/08 (0)
- Interesting. I would not expect a switch closure to cause a pop. - Al Sekela 15:21:08 01/11/08 (5)
- RE: Interesting. I would not expect a switch closure to cause a pop. - jea48 09:54:48 01/13/08 (2)
- It may well be the starting switch opening. - Al Sekela 15:36:31 01/15/08 (1)
- No switch on the motor.... This type of motor does not use one - jea48 20:24:11 01/15/08 (0)
- RE: Interesting. I would not expect a switch closure to cause a pop. - jking67 05:44:19 01/12/08 (1)
- The oil burner... - Al Sekela 16:48:37 01/12/08 (0)
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