Furnace blower moter sometimes needs manual spin

[Scott Long]

I have i think an intertherm furnace in my manufactured home. Its about 20yrs old. The motor sometimes hums but doesnt spin up. Its not every time. When it does i can (carefully of course) manually spin start and flip switch and it goes. Like i said though, sometimes it spins without help. I replaced the capacitor of course going cheap 1st,...same. I was just wondering if it sounds like motor for sure. Would it start okay sometimes though?

 

[Fitter30]

Try replacing the capacitor if that doesn't fix it you will need a motor. If replacing with a non oem motor do not go with one by hp alone. Your motor name plate amps 4.1- 1/4 hp and the replacement is 4.0 amps- 1/4 hp go with a 1/3 hp manufacturers play with np ratings.

 

[Sponsor]

 

[Plumber69]

I have i think an intertherm furnace in my manufactured home. Its about 20yrs old. The motor sometimes hums but doesnt spin up. Its not every time. When it does i can (carefully of course) manually spin start and flip switch and it goes. Like i said though, sometimes it spins without help. I replaced the capacitor of course going cheap 1st,...same. I was just wondering if it sounds like motor for sure. Would it start okay sometimes though?

Same Uf capacitor. Usually marked 5uf 7.5uf could be 10uf

 

[Fitter30]

Need to pull it to see if it's not marked it might be on the motor label

 

[Scott Long]

Yeah, as mentioned...i already replaced capacitor. Yes it was the 7.5. I was hoping it was the cheaper fix....nope

 

[Scott Long]

...and update. I just had to manually spin start. It was very slow to get going...slowing gaining rpms.

 

[Scott Long]

The label inside furnace door told me which capacitor i needed. Im just curious from others experience if this sounds like a weak motor dying? I found it odd...sometimes it starts up by itself and sometimes needs help.

 

[WorthFlorida]

Is this a forced warm air furnace? What is the model number and fan motor? Most are multi-speed motors. Speed is controlled by either by dip switches for speed or a wired plug with several plugin slots. For cooling the fan runs a higher speed and for heat, slower. This is for older systems before ECM variable speed motors.

You can try changing the fan speed settings to see if that gives better results but sounds more like that the motor is going bad. Switch the thermostat for cooling, if this is a heat pump with electric heat or and AC only with electric heat, lower the thermostat to turn on the AC. The motor should run at a higher speed. If the fan runs more reliable at a higher speed, then the motor is going out but it may buy you time to get a motor and have heat.

This is a poor video but it'll give you the idea how to change motor speeds.

 

[DavidDeBord]

The label inside furnace door told me which capacitor i needed. Im just curious from others experience if this sounds like a weak motor dying? I found it odd...sometimes it starts up by itself and sometimes needs help.

Scott,... With You replacing the Capacitor, & still having to manually spin the motor, the only possibility is that the motor is getting ready to "Bite th' Dust".

The only other possibility, is that the Capacitor & Motor are not a match, which You can only determine by literally reading the Motor Data Plate, which since it is an "Intertherm", that is entirely possible.

If Your replacement Cap, is what is required,.... Then if this motor is permanently lubricated, & not one that requires seasonal Oiling (Oil it if it does require oil), then You will need a New Motor & Cap.