Little Known Pump Error

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Ev
A Heck of A Nice Guy

The only solution is to replace the whole pump.

In this case it is the Maytag MHN33 with this problem, however the drain pump is similar in many washers so if you have the same situation in a different brand check out the pump.

If the impeller moves from side to side and sticks out like what is shown in the picture that is the cause.

There can be a little play in the impeller and shaft moving but they shouldn't stick out away from the pump with a gap like shown. What is happening is the sometimes the impeller is moving away from the pump housing during the wash or spin cycles. This causes the pump to malfunction and only drain part of the water. This might be because water is getting behind the impeller face and into the pump or since the impeller is sticking more forward the magnets of the motor can't spin the impeller as efficiently. Either way this is the problem. Just to test the theory I left the impeller sticking out as far forward as I could and reassembled the pump and tried a cycle. It immediately failed. I took the pump back out and made sure the impeller was seated properly and ran another cycle and all was fine.

This is what the impeller should look like properly seated in the pump.

Take out the 2-4 screws that hold the pump housing.

Notice in this picture how the impeller is not flush with the grey round opening in the pump housing.

Visually check to make sure there is nothing blocking the impeller.

Disconnect the electrical plug.
You can do this first before the other steps if you want.

Disconnect the hoses. Have a towel or two underneath the pump and hoses to catch all of the water coming out of the hoses.

Remember the larger foot has a rubber base on it that has a metal tab from the floor of the washer sticking into it so you have to move the pump as far to the right as possible and lift up and to the right.

Slide the whole pump to the right to move it out of the holes. The smaller leg will probably come out first and easiest.

Here is the tip Al told me. Remove the pump. 

I put my finger by the impeller and could spin the blades easily so I knew there was nothing stuck.

What was weird is that the impeller shaft seemed to move back and forth very easily to the left and right rather than just the impeller moving.

The pump felt very hot as if it was burning out, but yet I heard and saw it pump water out on a regular basis.

Set the washer to do a spin so it drains all of the water out.

I went though the usual checks of the pressure switch and the drain pump. Nothing was in there. All seemed fine.

I kept having this error on two particular machines. I bought them both at the same time and they are consecutive serial numbers. I thought it was odd that they both had the same issue but I figured the cause had to be related because they were made at the same time.

I ran several test loads through with rags and towels and even a sleeping bag. They all washed fine.

Then I ran two loads with nothing in the machine and both times there was clean water in the tub after the cycle and F21 error code on the screen.

This particular example is using the Maytag MHN33 washer but other brands with similar washers might have the same type of error. Thanks to Al, a technician from WASH, for explaining this problem and letting me in on the cause.

You may notice that you have a machine or two that is often showing an F21 error code. You clear it on the key board and everything runs fine for a time or two. Then you check the pump and drain screen 

and that seems fine and it runs fine for a few cycles and then it happens again. There is no particular pattern. It just happens. Frustrating for you and customers.