Sigh..I think I have a dead blower motor

[Torn Mind]

Motor has the symptom of start, but not catch. It will run for a second and die constantly without end

I changed the run capacitor today, in which the old one tested bad at 6.4 MFD. The new one is a quality AmRad that read 8.0 MFD before installation. The symptoms remain.

So yeah, is my conclusion correct?

 

[NutBucket]

Probably a bad winding. If you can figure out the frame size you can get a replacement for around $100.

Or, you may be able to find a shop to rebuild yours. Those aren't so common anymore.

 

[master_shake_]

hit it with a hammer.

seriously.

 

[NutBucket]

That only helps if it's stuck on a bad winding or similar. Not a long term fix.

 

[natto fire]

hit it with a hammer.

seriously.

That doesn't work with an induction motor, and as pointed out, is only a quick fix for a universal motor. Great if you are stranded in a parking lot and suspect the starter is bad, not so much for household devices. If the motor has a capacitor, then it is likely an induction motor, does not have brushes or an energized rotor, and this trick doesn't work.

Sent from my XT1585 using Tapatalk

 

[master_shake_]

That doesn't work with an induction motor, and as pointed out, is only a quick fix for a universal motor. Great if you are stranded in a parking lot and suspect the starter is bad, not so much for household devices. If the motor has a capacitor, then it is likely an induction motor, does not have brushes or an energized rotor, and this trick doesn't work.

Sent from my XT1585 using Tapatalk

worked on my furnace blower.

 

[NutBucket]

Must be a shitty unit as even 30 year old HVAC systems I've worked on use induction motors. Generally, more efficient and last longer too.

 

[master_shake_]

Must be a shitty unit as even 30 year old HVAC systems I've worked on use induction motors. Generally, more efficient and last longer too.

it was from the 70's

even had that retro disco charm.

 

[Torn Mind]

Well, this is getting bizarre. So, tried bench testing by ohming the windings, and there are no short or open windings. Black to white has 3.8 ohms, which doesn't seem unreasonable.

So, next thing is just hooking up the wires properly and with cap installed and seeing if mains power runs it?

This a real what the hell. Motor cap was an issue, but there's another issue, and I don't know if this is mechanical or electrical, maybe bad control board?

 

[master_shake_]

hit it with a hammer

 

[natto fire]

Well, this is getting bizarre. So, tried bench testing by ohming the windings, and there are no short or open windings. Black to white has 3.8 ohms, which doesn't seem unreasonable.

So, next thing is just hooking up the wires properly and with cap installed and seeing if mains power runs it?

This a real what the hell. Motor cap was an issue, but there's another issue, and I don't know if this is mechanical or electrical, maybe bad control board?

Either do that, or put your meter leads on the wiring from the unit to the motor. A megohmeter "Megger" is usually used to check field windings on induction motors, as the higher voltage can hint at worn insulation.

If your air handler has resistive heating coils in it, there is probably a time delay relay for the blower, which could be bad.

 

[Torn Mind]

Either do that, or put your meter leads on the wiring from the unit to the motor. A megohmeter "Megger" is usually used to check field windings on induction motors, as the higher voltage can hint at worn insulation.

If your air handler has resistive heating coils in it, there is probably a time delay relay for the blower, which could be bad.

It's a furnace.
Sadly, I don't have a megger.

Although, situations like these makes it seem that a clamp anmeter is going to be a future purchase for me to compliment the "regular" one I already have.

 

[Paperdoc]

About a year ago the two-speed blower motor on our furnace (about 25 years old) burned out. New one was about $175 or more. I called a furnace repair guy I had bought parts from before and he had a matching used one. I drove to his shop and he sold it to me for $25 including a new pulley. Quick and easy fix.