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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.
It looks like there's a lot going on here, what with all those alphabe
Got a fun exercise for you today: let's use our electrical and schematic know-how to figure out how a circuit works in a schematic that leaves out a lot of useful labelling.
The circuit we're interested in is the one labelled Door safety interlock.
Based on its name and its context within the schematic -- it gates Line to a number of loads elsewhere in the appliance -- this circuit contains the door switch and the door lock. But how exactly does it work? We can assume that the sw
Sometimes, the hardest part of being a tech is dealing with the customer. Customers always have expectations, some reasonable and some not, and we have to manage these on top of performing our diagnostics and repairs.
A large part of being a real technician is knowing when to trust your own expertise over customer demands. This struggle generally manifests in two ways:
1. The customer has their own diagnosis that they're sure is correct. We've all encountered this before. Something alo
We've got a tricky one for you today: a Frigidaire-built Kenmore electric dryer that only runs on heat cycles. If you set it to a timed or auto dry, it runs just fine. But set it to air fluff, and you get nada -- no motor rotation, no nothin'. Sounds like a bad timer, right? That was our first thought, too. But like any good tech should, we covered all of our bases before jumping to conclusions, and what we found was much more interesting...
We'll start by analyzing the circuit of the motor
We've got an interesting one for you today -- take a look at the "IDI Motor" in this schematic:
That's the ice dispenser auger motor in this fridge, and there are a couple interesting things to figure out about it. First, what's the deal with its power supply? If you look at the label on the motor, you'll notice that it says:
So that's a 120 VDC motor. How does that work?
A quick look through the documentation tells us that this motor is designed to run in two differen
Here's a puzzling scenario on a Samsung refrigerator: the ice dispenser door keeps opening and closing nonstop.
When you encounter a weird problem like this, it's easy to lose your head and just start throwing parts at the machine and hoping one of them will fix it. But it's always important to keep our fundamental troubleshooting principles firmly in mind. In this particular case, troubleshooting is made even more difficult by Samsung providing us with a very low-resolution schematic -- bu
Some techs long for the "good old days" of mechanical controls, when troubleshooting appliances was supposedly simpler. But the universal use of electronic controls nowadays actually provides many troubleshooting benefits -- in particular in the form of error codes and diagnostic modes.
The purpose of error codes is for the control to tell you its best guess of what's wrong, based on the algorithms programmed into it by the engineers. Note that the engineers' best guess is sometimes a very
Sealed system thermodynamics is a deep well, but fortunately, you only need to skim the surface to gain a functional understanding. And as techs, it's this functional understanding that we need to acquire in order to effectively troubleshoot.
To do that, we're going to cover the three central concepts to understanding a sealed system: saturation, subcooling, and superheat. Let's start with the one upon which the other two hinge: saturation.
In order to talk about what saturation is, we
Why is it that manufacturers (such as GE, Electrolux, and others) always recommend that you seal any splices you make in their refrigeration units with silicone grease? The simple answer is that it keeps out water. This is obviously desirable because water can both corrode and short out electrical connections. A splice is already a weak point in a circuit, so especially in wet environments, you want to give them as much lasting power as possible.
And it gets even more interesting when you'r
Information has always been the name of the game for appliance repair techs. Our jobs are all about locating and making extrapolations upon information such as specifications and measurements. If we can't access at least a baseline level of information for a particular job (at the very least the schematic), then it's almost impossible for us to do our job.
The meteoric rise of mobile technology and the Internet over the past few decades has hugely expanded how much information we can access
Imagine you're out on a call, and you run into this:
As the picture says, the dryer runs like this. And even weirder, when you correct the wiring, it stops running.
Take a minute to think, then see if you can answer this pop quiz:
1. How does the dryer run in this configuration?
2. What's wrong about the wiring in this configuration?
3. Why does it stop working when you correct the wiring?
4. What one test could you do that would prove your hypothesis about th
Many appliance repair techs are intimidated when it comes to troubleshooting control boards. When we talk about "control boards," we're really talking about a single-board computer. After all, we are talking about computers here -- computers that just so happen to run appliances. Samsung is especially famous among techs for being “too electronic” or using too many control boards. Many techs will install a replacement control board from Samsung without running a single test, just to avoid the hea
At ASTI 2025 in Orlando, FL, I had the honor of teaching a class on reading schematics and troubleshooting using Master Samurai Tech's patented Ten-Step Tango troubleshooting technique. During that class, we did diagnostic workshops on a number of different scenarios, all of which were taken from right here at Appliantology. For those of you who couldn't make it out for the convention, let's run through one of those scenarios here.
We'll be running through the steps of the Tango, but for th
Tell me what's wrong with this picture:
No, your eyes are not playing tricks on you -- that schematic really is showing a split-phase compressor being run by an inverter board.
If you're sitting there sputtering and foaming at the mouth in disbelief, thinking, "That can't possibly be correct," then congrats! You had the correct reaction. What this diagram is showing simply can't line up with reality. Split-phase motors are never run using inverter boards -- the very idea is nonse
There's a goal that any tech worth his salt should have when he heads into a service call: troubleshoot the machine until he has logically and definitively located the problem.
Most of the time this goal is achievable, as long as you have the documentation for the appliance you're working on. You can take measurements and compare them with the specifications from the manufacturer until you find what's not within specifications. This is called analytical troubleshooting and is, in fact, the
You're fighting a constant battle in the appliance repair trade to get the most money out of the time you spend. One of the biggest problems you face is unprofitable service calls. Most often these crop up as repairs that are close to the replacement cost. What customer is going to opt for a $300 repair when they can buy a new dryer for $400?
Fortunately, there are 2 simple steps you can take to weed out 95% of these kinds of calls. These steps are prediagnosis and flat-rate pricing.
P
There are some electrical terms that are often used in vague and incorrect ways by the general public. This can make things confusing for us techs, especially those new to the craft, because these terms have precise meanings when used by those in the trade. A couple of these words are short and ground.
Short is often used by the non-technical to refer to any "bad" circuit. The term "short circuit" is a popular one to throw around in this sense. In reality, a short is just one of multiple di
New technologies are never invented specifically for household appliances. We always get hand-me-downs. But just because a technology was used first in a different field doesn't mean that we're familiar with it already when it reaches appliances.
TMR (tunnel magentoresistance) sensors are one such example. Coming to us from the world of computer electronics, they serve the same purpose as Hall Effect sensors but work completely differently.
A TMR sensor consists of two ferromagnets sep
Take a look at the cooktop schematic below.
I don't know about you, but "tranformator" isn't a familiar term to me. it certainly sounds like a transformer, but why would a transformer be necessary in a 240 VAC cooktop element circuit?
The best thing to do here is to look up the part numbers for the "transformator" as well as other key components, such as those cooktop switches that the transformator is supplying power to. Then we can use a parts site to look at physical pictures
Thermistors are everywhere in appliances these days, and they're a relatively common-fail item, so wouldn't it be nice to stock a supply of them in your service vehicle to be used on any occasion?
Well, in order to determine how feasible that is, we need to answer a question: are all thermistors interchangeable?
The short answer is no. The long answer is that thermistors are not interchangeable brand-to-brand, but they can be interchangeable within the same brand, depending on the manu
Take a look at this motor circuit:
Three different windings? Triacs in the circuit? A "sense resistor"? What's going on here?
As it turns out, there's nothing really new or different happening here. In fact, all we're looking at is a standard split-phase motor with two different start windings. One is the start winding when the motor functions as a drain pump, and the other is for when the motor functions as a wash pump.
Here's what the circuit looks like when the drain wind
One of the first steps when you're troubleshooting a warm temperature proble in both compartments of a refrigerator should always be to identify whether you're dealing with a problem in the sealed system or with a problem elsewhere in the unit.
The go-to method for most techs is to get eyes on the evaporator coils. While the frost pattern there can tell you a lot of things about the health of the refrigerator, it has a massive drawback: getting to the evaporator can require a lot of non-tri
Volts, ohms, and amps -- these are the three types of electrical measurements from which we draw our diagnostic conclusions as appliance techs. They all have their uses, but watch out -- they're not all equal in usefulness or reliability! Let's go through them one at a time.
Ohms: Despite being a lot of techs' go-to measurement, ohms is actually the least reliable of the three. This is due in large part to the fact that it can only be performed on a dead circuit. This means that it complete
One of the first things you need when you start working on an appliance is the model number. Otherwise, unless there's a tech sheet with the machine, there's no way to find technical info on it. But what do you do when the model number tag has been damaged or removed? It's a rare occurrence, but one that can cause a major roadblock in a repair. Here's an example of one such situation:
As you can see, both the model and serial numbers are almost entirely illegible. Fortunately, there's
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