Repairing a Frigidaire Unimatic Washer Motor Start Switch

[Unimatic1140]

Tonight I worked on the final task on Jed's 1955 Unimatic washer and that was fixing the motor start switch. When we were bench testing it, it worked just fine, but once put back into actual service the switch started to act up and was not working properly. So I photographed the whole procedure so everyone can see what is needed to be done.

First here is what I was working on:

All AC washer motors have two sets of windings, START and RUN. To get the motor moving from a complete stop it needs a bit of an extra kick so two windings are needed, once its up to full speed only the RUN winding is needed and the START winding is turned off. Two problems can happen if the switch is not working properly:

#1. If the START winding is left in the circuit (powered on) once the motor is up to full speed it is going to overheat in a few minutes and smoke.

#2 If the START winding is not put in the circuit at motor start up (powered off), the motor will just hum as it will not have enough force to get it moving.

To switch the START winding on and off the motor has a part called the motor start switch. It operates via centrifugal force, once the motor is up to full speed, centrifugal force moves a plunger out of the way and the switch moves upward via spring action removing power from the START winding.

The following will show you how to remove the pump, motor bottom and motor start switch in a Unimatic. The transmission does not need to be removed for this procedure.
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[Unimatic1140]

Turn the washer on its side and remove the four screws that hold down the cross brace.

 

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Here is a trick for screws that are stuck. If you have trouble getting a screw to turn and/or its stripped, use a pair of vice grips. Lock the vice grips to the side of the screw really tight and get the screw turning counter-clockwise. Once you loosen the screw with this trick you should be able to use your screwdriver to remove the the screw the rest of the way.

 

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Remove the cross brace by shifting it downwards and then outwards. Be careful not to let the snubber plate and spring fall off when you remove it.

 

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Once you have the cross brace off be sure to support it with something tall enough to keep it level and keep the pressure off of the mechanism support. I happen to be using a 1965 coin op deep action agitator, it works perfectly.

On reassembly be sure to sand and thoroughly clean (with solvent like paint thinner) the pump base and snubber plate.

 

[Unimatic1140]

Place something under the pump plate to catch the water that is going to fall out and remove the eight pump plate hold down screw. Remove the plate.

 

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Now you need to put one screw back into the pump to hold it steady while you remove the impeller mounting screw. Also wedge a screwdriver between the fan blades and the pump to keep the impeller from turning.

 

[Unimatic1140]

To remove the impeller mounting screw that sits in the middle of the impeller, first heat it gently with a torch. Next take the VERY LARGE FLATHEAD SCREWDRIVER and clamp a vice grip to it for leverage. Turn the screwdriver counter clockwise using the vice grip as a handle, use your other hand to firmly push the screwdriver into the slot in the screw.

 

[Unimatic1140]

Look Ma, no special tools needed!

Now here is a trick, normally you would need the Frigidaire Unimatic impeller puller special tool. But you can heat the impeller center again, take your vice grip and lock it to the edges of the impeller ridge and pull straight out. Be careful with the heat because there is a rubber seal beneath it and you don't want to over heat and melt that seal.

 

[Unimatic1140]

With the impeller now off you can remove the pump housing (hoses still attached, just push it to the side) and the motor fan.

 

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Now you remove the four motor mounting bolts. Try and pull the bottom bell of the motor off, you might need to pry it to get it started.

 

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On Jed's washer, like a few others I've seen the motor shaft was stuck in the bearing and it doesn't want to come off. I don't take no for an answer with machines, so out comes my trusty gear puller.

 

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With the bottom bell off you can see the plunger that rides outward when the motor rotor gets up to full speed. This plunger holds down the motor start switch until its forced outwards which allows the start switch to pivot upwards and turns off the START winding.

 

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Next remove the 2 start switch hex screws and pull the switch plate and base off the motor bottom bell. The four areas circled in yellow need to be thoroughly sanded and cleaned. These are the actual contacts.

 

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Reinstall the motor end bell and then attach a multimeter to the contacts and test it both with the plunger in and manually move the plunger out with your finger. Make sure you have 0 ohms with the plunger in and no continuity with the plunger out.

 

[Unimatic1140]

Once you fool with the start switch it can get out of adjustment. That is why you must test it, I found that it wouldn't make contact no matter what now, so I pulled the motor end bell back off and removed a few of the spacers that are on the end of the motor rotor. I reinstalled the bell and it now works perfectly.

 

[Unimatic1140]

Reassembly the machine back in the same order. When you reinstall the pump screw be sure to put some Loctite Threadlocker on the threads to prevent the screw from loosening. If the screw gets loose the fan will rattle and make a loud annoying sound. Be sure to tighten the impeller screw REAL TIGHT.

Don't forget to sand and clean the snubber plate and pump bottom plate as well as shown in the fourth picture in this thread!

Yay for Unimatics, the most fun washers ever.

 

[mickeyd]

I love pumps and this is my first time seeing a Frigidaire&#

The impeller is a shock. Was expecting something huge because the water flow is so fast, but i guess at 1140 rpms, anything bigger and the Uni would be airborne^

Perceiving correctly, right? --that little blender blade in 159 is the impeller.

 

[tuthill]

AWESOME

Once again Robert, I cannot thank you enough for all your generosity (and not just when it comes to washers either!). I am so excited to have a working Unimatic... I can't wait to move it into the laundry room

 

[tuthill]

Hi Mike

I assume you think the deal right in the center (with the screw in it) is the impeller... I though the same thing at first too. The impeller is actually on the other side... A whole bunch of ridges are mounted along the rim of the pump... that's what moves the water.

 

[mickeyd]

Is there a pic? Dying to see it

;'D

 

[tuthill]

Hey Mike, the ridges around the edge are what move the water... Still not as fast as a Maytag though

 

[maytagbear]

Fascinating, Robert, just

fascinating!

Thank you, thank you.

Lawrence/Maytagbear

 

[gyrafoam]

The old repair people referred to the part in Robert's hand (see photo #303165 as the "skillet".
A great tutorial!

 

[tlee618]

Robert, once again thank you so much for taking the time to photo each step and explain it in such detail for us. Probably won't ever have the chance to do any of this but it is great to see and understand what others are talking about. Terry

 

[a440]

Awesome Photos!

Thanks for the great, up close, step by step photos!
You should do a updated repair guide book! I am sure that you have other tricks that they don't mention in the older books due to the machines being so much older now!
Brent

 

[swestoyz]

Thanks again Robert - I'm sure that this will be a thread that will be searched for in the archives for years to come.

Ben

 

[mickeyd]

Thanks Jed, that explains a lot

Been down and in the Uni, but never had the pump apart. But when watching all the fabulous goings-on, the fan, the spin-switch, etc., have spent many moments thinking about what's inside the pump. It's huge, as pumps go, and although strong, agree it's no Maytag or Easy Spin. Having only known the winged impellers, could not figure out how an impeller as big as would be needed to fill that space and revolving at 1140, did not send the water out in 10 seconds rather than 60. Now I see it. Those little fingers or toes surrounding the wheel cut way back on the flow. Hail to the Frigidaire engineers and their wonderful "mechanism." Pure genius.

Gotta love how on the back of the WO 65, above the "viewing window, " it says: " MECHANISM MUST BE BOLTED DOWN...." All those amazing moves from one unified giant cog, and that's all that's down there. Amazing.

Got a Unimatic picture story brewing, but I'll wait a bit.;'D

 

[tuthill]

Got a Unimatic picture story brewing

Can't wait! Your stories are always very entertaining