Water level sensing in LG washers is done differently from how you may be used to seeing it done in other brands. Whirlpool, GE, Electrolux and others use an air tube connecting an air dome on the tub to a pressure sensor with a physical diaphragm or transducer that "feels" the water level increase as an increase in pressure inside the air tube. LG uses frequency measurements. How's that again? I'll let Brother john63, Dean of LG Appliantology explain:
The Water Level Frequency Sensor operation is based on the displacement of the *coil* attached to the diaphragm.
When the *coil* raises or lowers---it changes the electronically resonant characteristics of the oscillator circuit.
The water level is measured by the Main Board---by frequency readings.
I've never had a failed Water Level Sensor.
It is best tested while on the washer---by using the TEST MODE.
On most LG washers---the Test Mode is enabled by pressing and holding the SPIN SPEED and SOIL LEVEL buttons---and then pressing the POWER button (release all 3 buttons and wait for the door to lock).
Press the START / PAUSE button 4 times at one second intervals (Prewash Cold Water Fill)
The display read-out on the Control Panel will show the *frequency*
Empty---the frequency read-out should be about 255
A tub full of water should show a frequency of about 214 (depending on model number)
Some of the errors that can be displayed---relating to water fill are...
Little or no water---usually caused by a failed Water Valve
Too much water (overflow detected)---Can be a failed/stuck open Water Valve or blockage in the black air tube which is connected to the Water Level Frequency Sensor. Disconnect the tube from the sensor---and blow air back into the tub to clear obstruction.
To test the Water Level Frequency Sensor outside of the washer...
Use a test meter to check the ohms between pins 1 and 3 (should have between 21 & 23 ohms).
These new Whirlpool vertical modular (VM) top-loading washers are pretty easy to troubleshoot, mostly because they practically troubleshoot themselves with fault/error code combinations that you can read in diagnostic mode.
The mode shifter has turned out to be one of the common-fail parts on this washer and it's regular rolling inventory for me. Although the fault/error codes will point specifically to the mode shifter if there's a problem with it, there may be situations where you want to test the mode shifter directly. Brother Eric calls the dance steps on that little ditty:
Yes, you should have 5vdc at J2 pin 2 (pink) with connector disconnected. This is a digital logic level provided via pull-up resistor on the control board. The rpm sensor in the shifter will "pull" this level low (0 volts) each time the optical sensor light path is interrupted by the rotating blade inside the transmission. This creates a digital square wave to the processor (switches between 5vdc and 0vdc). The frequency of the square wave is dependent upon speed of rotation of the transmission and is calclulated by the processor to determine rpm. If you monitor J2 pin 2 while wire harness is connected and rotate the tub very slowly, you should see it switch between 5vdc and 0vdc. You should also have 5vdc on J2 pin 1 when in spin mode and 0vdc when in agitate mode.
The new inverter compressors ain't like the old skool compressors used in yo momma's beer cooler. Oh, they still do the same basic job-- pump refrigerant vapor. But you have to troubleshoot them differently from the old skool compressors. In their quest to comply with increasingly onerous Energy Star requirements, all the appliance manufacturers are producing refrigerator models that use inverter compressors. Like it or not, inverter compressors are here to stay. Many a fine tech has been befuddled by these new compressor systems but not you! For the Samurai shall reveal the truth unto thee, and the truth shall set thee free.
Conventional Old Skool Compressors
Before we talk about how these inverter compressors work and and how to troubleshoot them, let's quickly review the old skool compressors so it's fresh in our mind when we compare with how the inverter compressors work.
In the conventional compressor technology that's been around for decades, the compressor has a start winding to help kick things off and a main (or run) winding that keeps the compressor going after it's started. A start relay and sometimes a start capacitor are used to momentarily power the start winding and then take it out of the circuit once the compressor is up and running. The compressor runs off standard, single-phase, 60 Hz 120vac.
If the start relay fails, the compressor will sit there trying but failing to start and drawing locked rotor (LR) current. Where the normal operating current draw on a conventional compressor is somewhere between 1 and 2 amps, LR current could be somewhere north of 8 amps. All that current makes heat, lots of heat. As the compressor sits there straining to start, it starts boiling the oil and burning the varnish insulation on the motor windings. If this goes on for very long, the compressor will literally self destruct (internally) from all the heat.
To prevent this unhappy scenario, the engineers added an overload device that's used to kill power to the compressor if something goes wrong, like a bad start relay, open compressor start winding, bad internal bearing, or a seized piston inside the compressor that prevents it from starting correctly. The idea being that if the problem is just a bad start relay (very common), this can be repaired easily and inexpensively compared to replacing the entire compressor (or refrigerator).
If you were to measure the resistance of the start winding and the main (or run) winding, you would find that the start winding has a much higher resistance. This is because the start winding is made of thicker wire to handle the extra current flow through it that's needed to get the compressor piston going from a dead stop.
A common troubleshooting technique with these old skool compressors is to rig up a test cord and manually power the compressor to see if it'll run. More details on compressor test cords here: http://appliantology...e-a-compressor/
Once they're up and running, these old skool, compressors run at the same speed and move the same amount of refrigerant vapor per minute. In other words, their refrigerant capacity and motor RPM is constant the entire time it's running. They can't work "harder," just longer.
So, let's summarize the old skool compressors: - has two windings, a start and a run winding, which are physically different windings and have different resistances; the start winding has higher resistance than the run winding - runs off standard 120vac household power - uses a start relay to initially power the start winding and then take it out of the circuit after the compressor is up and running - can rig up a test cord to directly power the compressor - are constant capacity and speed machines
Keep all this in mind as we now look at the new inverter compressors...
Inverter Compressor Systems
Although inverter compressors do the exact same thing as the old skool compressors-- pump refrigerant vapor-- and they physically move the vapor the same way-- through a vapor-compression cycle-- they are powered and controlled very differently.
For one thing, inverter compressors use a special three-phase voltage produced by a special control board called an inverter. Fuggetabout 120 VAC, 60 Hz line voltage. We're not in Kansas anymore, boys and girls! Both the amplitude (amount) and frequency of the input voltage will vary. Typical specs are 80 to 230 VAC with the frequency ranging anywhere from 57 to 104 Hz. The higher the frequency, the faster the inverter compressor will run.
So, inverter compressors, unlike their old skool forebearers, really can work harder. In fact, this is exactly why the manufacturers are using these inverter compressor systems; they can match how hard the compressor needs to work to the actual refrigeration work needed to keep the beer cold. By doing it this way, the compressor draws less power and the manufacturers can meet the Energy Star requirements.
Inverter compressors have three windings, not just two like the old skool units. All three windings should have the exact same resistance. If the resistances vary from each other by as much as a 1 ohm, the compressor will not run correctly. In fact, this is one of the ways of checking an inverter compressor: making sure that all three windings have the exact same resistance. Check the manufacturer's spec for what that exact resistance reading should be. This is different from the old skool compressors with just two windings and the start winding has a much higher resistance than the run winding.
Remember how a common troubleshooting trick with the old skool compressors is to power it directly with a test cord and see if it starts? Don't try that on these inverter compressors because you'll permanently break it. If you're a professional Appliantologist and you do this on a service call, you just bought your customer a new refrigerator!
Let's summarize the inverter compressors: - have three windings, not just two; all three windings have the exact same resistance - does not use a start relay/overload device - runs off a special voltage produced by an inverter board; the voltage varies in both magnitude and frequency: the higher the frequency, the faster the compressor runs - variable capacity, variable speed - cannot directly power the compressor (well, you could but you'd regret it)
Troubleshooting Inverter Compressor Systems
If you're working on an inverter compressor system where the compressor isn't running, you can't power an inverter compressor directly to test it. But you can (and should!) check the resistances in all three windings to rule out an open winding. If the compressor windings check good, this is not diagnostically conclusive that the compressor itself is good. But if, OTOH, the winding resistances are imbalanced or one of them is open, this is diagnostically conclusive that the compressor is bad.
Okay, so let's say the compressor windings check good but it's not running. Now what?
Now you have to check the inverter board itself. There are two different tests you can do on the inverter board to see if it's good or not:
1. Check for good input voltages.
An Inverter board will have two different input voltages: - 120 VAC main power supply - 4 to 6 VDC control voltage from the main control board (or Muthaboard-- a completely separate circuit board in the refrigerator)
If you're missing one of these voltages, the inverter board can't run the compressor. You'll need to backtrack and find the missing voltage. Could be a bad wire harness connector, bad muthaboard, etc. BTW, make all voltage measurements with everything CONNECTED. Otherwise, you'll get different readings that could be misleading.
OTOH, if you're getting both of these input voltages to the inverter and the compressor isn't running (and you've already checked the compressor winding resistances), then you need to do this next test:
2. Check the current draw on the 120 VAC power supply.
- Disconnect the 120 VAC power supply from the inverter board. - Connect your amp meter around one of the wires supplying 120 VAC to the inverter board (doesn't matter which one). - Reconnect the 120 VAC power supply to the inverter board and watch your amp meter.
If the meter stays at 0 amps, the inverter board is toast-- it's not even trying to start the compressor.
If you see the current draw jump to say 4 amps (typical LR current in these inverter compressors) and then drop off, keep watching. Most inverter boards will repeatedly try to power up the compressor. On GE refrigerators, for example, the inverter will try to start the compressor 12 consecutive times. If the compressor fails to start, the inverter will timeout for 8 minutes and then try again. Other manufacturers may have different test schemes but the idea is the same: if the inverter is working properly, you'll see activity on your amp meter as the inverter tries to do its job.
In the video below, I demonstrate troubleshooting an inverter compressor system on a GE refrigerator. The only thing I didn't show in the video is checking the inverter board's current draw. (Kudos to Brother denrayr for posting this comment on the Youtube page for this video!)
Both the upper rack stop and roller assembly in the Whirpool-KitchenAid dishwashers are amazingly simple to install... IF you know the trick. Ain't that the way it always is in appliance repair: it's all a cake-walk IF you know what you're doing. And that's a big fat IF.
Problem is that most people don't know what they don't know but they THINK they know it all. Case in pernt:
Had a customer call me yesterday (Saturday) because the upper rack in their dishwasher came out. They insisted that I come right out. I told them that upper racks in dishwashers don't just come out on their own; great pains are taken during the design and manufacturing process precisely to ensure that this doesn't happen. Can you say, "class action lawsuit?"
I advised my customer that something had broken in the upper rack assembly to cause this unhappy condition, typically the rack stop or the rack rollers in the Whirlpool-Kitchenaid designs, and there was no reason for me to come out right away because I didn't have the needed parts but could order them and come out early next week. They insisted that I come right out because they KNEW nothing was broken.
So, in an effort to provide good service and giving the benefit of the doubt, I agreed to go out told them that they would be charged extra if it turned out that a part was needed that I didn't have (but knew would be needed).
And what did I find? Low and behold but the upper rack roller was had broken clean off!
They were appropriately contrite and embarrassed, paid for my service call fee for that day and will also pay full price for the repair when I return early next week with the needed rack roller.
Deadly Mistake Numero Uno: Using a gel detergent or powered detergent that is old or has already gotten wet.
The main tasks of a detergent are to remove soil from surfaces and prevent the re-deposits of soils on the surfaces. The best detergent formulations will be powdered. Do not use gels or liquid detergents.
Why powdered detergent? Because in today's phosphate-free world, you need two types of cleaners in a detergent formulation to get dishes clean:
1. Enzymes to remove protein-based stains 2. Bleach to remove other stains
These two cleaners are incompatible with each other-- if they're released at the same time, the bleach will destroy the enzyme and, after this epic battle, there will be little or nothing left of the bleach to do even its little bit of cleaning. The result: dirty dishes. They can coexist in a powdered form because they are not activated until 1) they get wet and 2) the water temperature reaches 125 deg. F. In a liquid or gel form, everything is already wet so you're only getting one kind of cleaning action.
Detergent has a shelf life. Old detergent will not work well because the enzymes denature over time. Also, the detergent must stay dry until it's time to use it. Once it gets wet or even damp, it activates and will no longer be active when put to work inside the dishwasher.
In my experience as a professional Appliantologist, my customers have enjoyed much better dishwashing results after I switched them over to Finish Powerball tablets. I leave two free samples behind and invariably, they report vastly improved washing results. BTW, I do not make a kickback for giving out the Finish Powerball samples-- I do it because the manufacturer, Reckitt Benckiser, puts on an excellent training seminar at the appliance training sessions I attend and it really does work well.
Deadly Mistake Numero Duo: Pre-rinsing dishes.
It is not only okay to put dirty dishes into a dishwasher, it is mandatory to properly activate the detergent! Detergents are designed to work with food soils, not clean water. Without the food soils, the detergent will create a caustic slurry inside the dishwasher which will etch the glassware by removing the silica from the glass.
Not only that, but pre-rinsing the dishes wastes water. DOE estimates that pre-rinsing dishes uses 20 gallons of water per load. Scrape the chunks off with a fork and leave the rest on the dishes. It's a dishwasher, for crying out loud! Let it do what it was designed to do!
Deadly Mistake Numero Trio: Not scraping the chunks of food or solid debris off the plates before loading them into the dishwasher.
Taken together, these last two Deadly Mistakes are a great illustration of the saying, "The opposite of dysfunction is dysfunction." People tend to fall into one camp or the other: they're either OCD pre-rinsers or they use the dishwasher as a garbage disposal.
You wouldn't believe some of the junk I've pulled out of dishwashers! Here's a short list of some of the things I've dredged up from deep within the bowels of broken dishwashers:
- plastic wrappers - tooth picks - bits of bone - broken glass - mayonnaise jar label - an adult human tooth! - crab leg shells - candle wick holders - ear rings - a tongue stud-- yes, a tongue stud!
Today's dainty little dishwashers can't handle hard solids and these things end up damaging the innards of the dishwasher such as breaking the macerator or binding the wash motor impeller.
So there you have it, the Big Three. Almost every dishwasher service call I go out on, the customer is doing at least one of the Three Deadlies. But not you! Nawsir, not no more 'cuz the Samurai hath done enlightened yo ace.
Since you slogged (or scrolled) through to the end of this post, here are a couple of bonus tips for getting the best performance from your dishwasher:
Tip #1: Use Rinse Aid!
It’s not an option with today’s dinky dishwashers. Rinse aid allows the dishwasher to use less water with the same amount of cleaning and drying effectiveness. It does this by creating what we professional appliantologists call “sheeting action” of the water. By making the water sheet along dishes, rather than cluster into beads, it evaporates faster and with less energy.
Tip #2: Do Routine Dishwasher Tune-Ups
No tools needed! Regularly using a dishwasher cleaner (Affresh) and performance booster (Glass Magic) to clear out the gookus and reduce the build-up will keep your dishwasher clean and fresh smelling and operating at peak performance.
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