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
PSC (Permanent Split Capacitor) motors are nifty pieces of technology that you'll most often encounter in Whirlpool's VWM washers. They operate a bit differently from your typical split-phase motors. Rather than having a dedicated start winding and run winding, with each winding having different specifications, PSC motors have two windings that are physically identical. The only difference between them is in what direction the windings are wound.
Another big difference between PSC motors an
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
In the appliance repair world, we deal with two different kinds of thermistors: NTC (Negative Temperature Coefficient) and PTC (Positive Temperature Coefficient). Don't know what those terms mean? Don't worry, I'll break it down for you.
Despite both being thermistors, the only real similarity between NTCs and PTCs is that the resistance of both changes in response to temperature. Beyond that, they work quite differently and serve very different functions.
Here's what a typical NTC the
What do you do when an appliance, despite all appearances of normality, simply refuses to do its job? The Samurai and I were forced to answer this very question today.
The culprit: A KitchenAid KGRS505XWH05 double oven all gas range.
The complaint: The customer told us that neither the top nor the bottom ovens would ignite, but the cooktop worked fine.
The customer's description turned out to be about right (for once). The upper oven broil and lower oven bake ignitors would glow f
We run into water inlet solenoid valves in many different situations -- washers, dishwashers, refrigerators -- so it's important to have a firm grasp on exactly how they work. For example, I just talked with a tech recently who was wondering why low water pressure can cause inlet valves to leak.
It seemed counter-intuitive to him, and he's not wrong. Wouldn't it make more sense for high water pressure to cause leaking? But once you learn exactly how these valves work, it will all make sense
Ever seen a capacitor somewhere in a split-phase motor's circuit and wondered what exactly the point of that thing is? That's what we'll talk about in this blog post.
There are two different types of capacitors in split-phase motor circuits: start capacitors and run capacitors. Each type has a different set of parameters and serves a different purpose. But before we get into these specific types of capacitors, let's take a quick review on capacitors in general.
Capacitors aren't compli
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
There's more than one way for a 3-way valve sealed system to be configured, and if you want to troubleshoot these machines right, you've gotta know the difference.
In the full webinar recording, the Samurai runs through 3-way valve operation and dual evaporator systems in detail, using Samsung technical documentation for reference. It's not one you're gonna want to miss!
Click here to watch the full webinar -- only available to premium members!
What we call Parts-Changing Monkeys (PCMs) around here at Appliantology are techs who rely on pattern recognition, tech myths, and blind luck to make their repairs. Case in point with this example of a GE ZGU385 gas cooktop, where said PCM figured he would get lucky by replacing a couple of components that seemed related to the problem, apparently without any troubleshooting beforehand.
Spoiler: he didn't get lucky.
Real technicians don't rely on luck to get things fixed. We rely on kn
@LearningTech dropped a great tip in The Dojo a little while back: not all LG control boards can be updated after a universal compressor is installed. If you're planning on doing sealed system work on these machines, you're going to want to check the list below to see if your model's PCB can be updated. Otherwise, you might be in for a nasty surprise.
LearningTech also provided a handy image showing where you can find a PCB's manufacturing date:
Want to be in on cool tech t
We've all been there: you're looking up the part that you need for the job, and the price tag about knocks you out of your chair. No way that heating element costs that much to produce! Maybe your concern isn't just for yourself -- you're interested in saving the customer some money.
Despite the sometimes exorbitant prices, there are many good reasons to go with the OEM part over a generic one.
OEM parts are generally better quality and make for a more reliable repair. You're going
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
Let's take a look at a multimeter and talk about what each function does and what it's good for. This is specifically for a Fluke 116 multimeter, so if you have a different meter, you might see a slightly different array of functions. But this will be representative of a typical multimeter.
LoZ: That stands for "low impedance". This is the loading function of your meter, meaning that it allows you to do voltage measurements that actually put a load on the circuit, allowing for a small
"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
Whether a control board in an appliance is simple or sophisticated, there's one trick it has to pull off: switching high AC voltage using low control voltage. They pull this off by using relays or triacs, devices that all of us are at least passingly familiar with.
But how do these very common control components work, exactly? And how is troubleshooting a relay different from troubleshooting a triac? That's what we'll look at today.
Relays: The older and simpler of these two devices, r
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're so used to our fancy control boards and computer-controlled appliances that we sometimes forget how to troubleshoot old-skool circuits. While these circuits are generally pretty straightforward, the manufacturers employed some clever tricks that can mess with your head if you don't have a firm grasp of simple AC circuits.
Take the buzzer in this dryer as an example:
The Tan or Black side of the buzzer goes straight to neutral through that unlabeled switch beneath the temper
You can't get around it -- you've got to understand at least the basics of thermodynamics to troubleshoot sealed system problems.
Let's say you're working on a two-compressor R134a refrigerator -- completely separate sealed systems for the freezer and the fresh food compartment. Two evaporators, two compressors... you get the idea. You're experiencing an issue where the FF is always too cold. Say, 20F or so. All the other components seem to be in spec, so you put a gauge on the low side of
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
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
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
Here's the situation: the tech is working on a dryer that keeps blowing its thermal fuse. The tech has already replaced the fuse once, and it's now blown again. What could be causing this, and what's the best way to tell?
We'll start by looking at the heater circuit -- an essential step in any troubleshooting plan.
Pretty simple stuff. Just a cycling thermostat, a centrifugal switch, and a hi-limit thermostat. The thermal fuse that keeps blowing is the one in the motor circuit. I
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