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Appliance Repair Tech Tips

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Bypassing the Auto Temp Control on a Whirlpool Washer


Son of Samurai

1,679 views

Here's your scenario: you're working on a Whirlpool CAM2742TQ2 Washer, and you've determined that the auto temp control (ATC) has failed such that it won't energize the water valves and allow the machine to fill. You intend to replace the ATC, but it's on backorder. Is there any clever trick you can think of that will at least get the customer going temporarily while they wait?

Time to crack out the schematic.

Screen Shot 2021-03-31 at 1.07.10 AM.png

It looks like there's a lot going on here, what with all those alphabetically labelled switches that the ATC controls. But what if we could just bypass all that? Let's look at how, with just a couple jumpers, we can rig this circuit to run whenever timer contacts 11 (for main wash) or 12 (for rinse) are closed.

Screen_Shot_2021-03-31_at_1_07_10_AM.png

There we go -- that's all we have to do! Those two red lines are just jumper wires, and that orange X is showing where we disconnected a wire.

The jumper directly to the left of the water valves means that, whether it's contact 11 or 12 that's closed, both valves receive power. The other jumper is there to completely bypass switch A in the temperature switch assembly. As for disconnecting the wire from terminal 5 on the temperature switch, that's just there to completely take the switch out of the picture.

Here's a markup of how the valves' power supply looks with contact 11 closed. You can figure out for yourself how it would work with contact 12 closed instead.

Screen_Shot_2021-03-31_at_1_07_10_AM-2.png

What are the consequences of this arrangement? Well, obviously the ATC has been taken completely out of the picture, so there won't be any automatic adjustment of the fill temperature. Furthermore, whenever the machine fills while rigged up like this, it will fill with warm water, since both valves will receive power. But that's just fine for our purposes, since this is a jury-rig to help the customer limp along until we get a replacement switch. As a bonus, you have definitely proven that the ATC switch has failed so you know for certain that the new switch will fix the problem.

Want to learn how to perform Circuit-Fu like this? Click here to check out our Core appliance repair training course over at the Master Samurai Tech Academy.

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There is nothing more permanent than a temporary solution that works.

 

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Vince Neibert

Posted

Very useful information! Well worth the time to read it.

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AARDL

Posted (edited)

My problem is I read this cool shit and when I need it I don't or can't remember.

Thanks Sam

Edited by AARDL
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  • Team Samurai
Samurai Appliance Repair Man

Posted

57 minutes ago, AARDL said:

My problem is I read this cool shit and when I need it I don't or can't remember.

That’s the cool thing about understanding circuits and technology— you don’t need to remember “tricks” because you can figure it out on-the-fly when needed. That’s why we teach the way we do.

Most techs think they need to remember “this trick” for Whirlpools, “that trick” for Bosch, etc. That’s a complete waste of diminishing brain space! All circuits work the same way because electricity works the same way all over the world. So you see a circuit, no matter who made it, and you can figure out stuff like this and much more that we show in the webinar recordings

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Ricky Bobby

Posted

Greetings oh great Samurai!! 
This is great info and advice ...thank you. Could you include a real board that’s been bypassed. Thank you so much. 

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  • Team Samurai
Samurai Appliance Repair Man

Posted

6 hours ago, Ricky Bobby said:

Could you include a real board that’s been bypassed.

In general, the way you would approach this would be to first determine the function of the board in the load circuit you want to modify. In other words, is the board generating and supplying a data signal or simply switching the power supply for the load of interest? If the board is producing and supplying a data signal, you can't bypass that. If the board is functioning as a switch, you may be able to bypass it with a jumper depending on how the load will function during normal operation without that switch in its circuit. 

Example: Evaporator fan in a Jazz board (Whirlpool) refrigerator. The board switches Neutral to the evap fan to complete the circuit and allow the fan to run. If the internal switch on the board fails open, the fan will never run even though it has unswitched Line voltage always supplied to it. Instead of replacing the board, you could install a permanent jumper on the board to always supply Neutral to the fan. The problem with doing this is that the fan will always run, even during defrost. Probably not desirable. The real utility in doing this with boards, though, is for troubleshooting and confirming the problem. This video shows an example of this: 

 

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