The general rule for dryer vent airflow is that, if the airflow feels like a breath (even a strong one), then you have a problem. This rule of thumb will serve you well a lot of the time, but sometimes a "calibrated palm" just isn't enough. Sometimes, you need to get an actual measurement of the airflow so that you can compare it to the specifications.
What you really want to know is the volumetric flow rate of the dryer exhaust. That is, how much air it's pushing out over a particular peri
We’ve all been hearing about R600a refrigerant for years now, and the reality is that it’s no longer an innovation in the area of household refrigeration; it’s the new standard.
With the majority of new refrigerators now being R600a models, repair companies need to be ready to perform sealed system repairs on them. This raises a few questions for these companies: how is R600a different from R134a, and what do I need to service R600a refrigerators?
R600a (let's just call it R600 from he
We're going to take a dive into what exactly is going on electrically with the high-voltage circuit in a microwave. We'll use this specific schematic as an example, but these principles apply generally.
Don't worry about most of the schematic. All that matters to us right now is the high-voltage section -- the transformer on the right side of the schematic and everything to its right.
If you're not familiar with how magnetrons work (or even what they are), then this circuit
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
BLDC motors aren't new technology in appliances anymore -- in fact, they've become the norm. As such, it's important to be aware of the different configurations you'll see these motors in across appliances. These configurations fall into three categories: 2-wire, 3-wire, and 4-wire.
An important thing to note before we continue: all BLDC motors in appliances are run by inverters. The inverter may be a separate board, like you'll see in washers with BLDC motors, or it may be built into the m
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
If you read my previous post about sealed system basics, you know that understanding the thermodynamic states of refrigerants (saturated, subcooled, and superheated) is essential to sealed system troubleshooting. In that post, I explained these states in terms of a simple pressure-temperature table. While that keeps things simple, it doesn't really give you a strong visual and mental model for how the refrigeration cycle works thermodynamically.
That's why we're going to spend this whole po
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
Let's crack out our schematic-reading skills and take a look at a seemingly straightforward washer lid lock circuit.
Notice that, while they give us labels for the pins, that's basically all we've got as far as specs or info about the control board's algorithm. So if we want to figure out how this circuit works during operation, we'll have to crack out some Circuit Fu™. That means using both our understanding of electricity and our understanding of the intended function of a lid lock
Ohm's law, meaning the set of simple equations that define the relationship between voltage, current, resistance, and power, is an essential tool for appliance techs. Not only is it the cornerstone of understanding electricity, but it's also an invaluable troubleshooting tool. This said, there are some loads to which the simple form of Ohm's law doesn't apply. The simple form of Ohm's Law only takes into account real resistance (ohms) but does not consider other ways that electron movement can b
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
If you're getting into appliance repair, or even just looking to downsize an overstuffed tool bag, you might be wondering: what are the absolute essentials that you should bring with you on any service call? Well, having my fair share of experience in the field, I'll put forward Team Samurai's list of must-have appliance repair tools. Note that this isn't supposed to be a totally comprehensive list -- just the bare essentials.
Multimeter with a loading/LoZ function
If there's a t
Here at Appliantology, our primary mission is to support appliance repair techs in performing prediagnosis: the method of performing as much troubleshooting as you possibly can before setting foot in the customer’s home. Prediagnosis is the biggest factor in increasing FCC (First Call Complete) rates, and the higher the FCC rate, the higher your company's profitability.
So how exactly does one prediagnose, and how does Appliantology help with that? Well, let's walk through the journey of an
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
By now, most of us are used to variable speed drive motor systems in appliances. The control board sends a PWM signal to an inverter, which tells the inverter how fast to run the BLDC motor.
While this is the type of inverter that's been used in appliances for years now, it's not the only kind of inverter out there. In fact, another type of inverter is starting to crop up in the appliance world, and it may very well become the norm for some applications. It's called a drop-in inverter, and
Anytime you work on a refrigerator with a control board, you've got multiple NTC thermistors in play. With how ubiquitous these devices are, it's important to know them inside and out -- especially how to test them. That's why we've made a webinar all about NTC thermistor technology for your viewing pleasure!
In this short excerpt from one of our many technical training webinars, we cover topics like:
What is an NTC thermistor used for and where will you find them?
What does
Whether you were aware of them or not, Hall effect sensors are everywhere. Any time you see a motor on an appliance with any kind of RPM feedback or speed signal, there's a Hall sensor on that motor. As with any ubiquitous appliance technology, it's important for us techs to know how they work. A deeper understanding of the technology means a deeper understanding of how to troubleshoot it.
So: what is a Hall sensor, and how does it work? These are semiconductor devices, so as with most elec
You're investigating a refrigerator that's not cooling properly, and you see the following bits of evidence:
Two questions for you to answer:
What (if anything) does the rime ice on the evaporator tell you?
The source of the problem with this refrigerator is present in one of these photos. What is it?
Let us know your answers in the comments, and we'll let you know if you're right!
Want to troubleshoot refrigeration problems like this (and much m
I want you to take a look at the door switch I've circled below. Think about it for a minute, then answer one question: what single test could you do to prove beyond a doubt whether or not that door switch is operating within spec?
There's no trickery going on here -- it's just a simple switch. But many techs will test it using a flawed, limited test that has a big chance of leading them to the wrong conclusion. And they'll do a bunch of unnecessary disassembly. Post your answer in th
"Ohms lie." It's become a popular phrase in the tech community, but what does it actually mean? Should you never do an ohms measurement? Are they completely worthless? Or is this phrase just another example of tech mythology?
The answer is more complicated than any of that. Let's run through a quick example to demonstrate. This is an old-skool Whirlpool gas dryer, just like they were cranking out left and right in the good old days.
Now, our scenario is a simple one: when we run
Here's a GE microwave schematic. There's a lot of typical microwave stuff going on here, but we're going to focus in on one component today: the monitor switch.
What exactly is this switch's purpose, and how does it affect the circuit?
The purpose of the monitor switch is to act as a safety to prevent the magnetron from being energized while the door is open. The door latch and switches in microwaves are designed so that, if everything is working correctly, the monitor switch sho
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
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
Let's say you're on a call for a Whirlpool GI6FARXXY07 refrigerator. You notice that the evaporator fan isn't running, even when the unit isn't in defrost. "Simple enough," you think, and you disconnect the fan harness and check its resistance.
Wow -- 500 K-ohms! No way that's in spec. Gotta be a bad fan motor, right?
Before we get too hasty, let's step back for a moment and do what we should have done at the start -- look at the schematic. When we do that, we can pretty easily locate
When it comes to troubleshooting BLDC motors and inverters, there's usually a standard strategy. You check the input to the inverter (a good 120 VAC power supply and a PWM signal from the main control) and you make sure the motor windings are in spec and all the same resistance. But what about measuring the output of the inverter?
This is certainly possible to do, and it can be a useful measurement, especially in hairier inverter troubleshooting scenarios. But before we get into that, let's
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