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“(with LETTER P BELLOW IT )”
“P” is just the wire color, purple in this case.
“NTC SENSOR CAN FUNCTION without a PCB ?”
The ATC switch has a crude little thermistor reading and switch circuit built into it. If you break one open, you’ll see a little board inside the switch.
“THE W thet is smack dab in the middle is neutral to the ATC SWITCH?”
Yes. That’s the Neutral supply for the switch itself. It needs a power source to do its job of reading the thermistor and controlling the power supply to the valve coils.
“and what is the line(marked with P right bellow ) running from the ATC SENSOR to the left connecting to to wire underneath the water level switch,in aid of? what its fuction?”
That is the Line supply for the valve coils that the ATC switch is switching to turn the valves on or off.
Just to add.. while vacuum cannot damage the tubing with the tools we use, pressure definitely can. Sometimes, you’ll need to pressurize with nitrogen to find a leak. Don’t exceed 200 psi or you could damage to relatively more delicate aluminum evaporator tubing.
Hi Scott. Keep in mind that learning the actual process of doing sealed system repair is a manual skill that you acquire by practice. But before you do that, it’s good to get acquainted with the process. And that’s where online learning and videos can help. The real strength of this course is in understanding how sealed systems work, how to diagnose them, and how to troubleshoot the electrical and electronic systems in the refrigerator. Doing system system work is just following a procedure. Here’s the dirty secret of the trade: most techs who do sealed system repair don’t actually understand how sealed systems work! THAT is what we teach online.
” If a technician contaminates his equipment somehow someway by unknowingly evacuating a hybrid system is nitrogen used to uncontaminated the equipment like nitrogen is used to clean a sealed refrigerator system? ”
Many technicians will not work on contaminated systems because getting rid of the different oil– mineral oil vs. polyol ester oil– is not 100%.But blowing out the system with nitrogen is a commonly used technique to purge the tubing of air and oil.
“What is “sweep-charging” being a greenhorn they are using terms and not sure what they mean by that term. Explanation would be much appreciated.”
Pressurize the system with refrigerant and then release. Repeat three times. Was a good technique back in the day. It’s not used so much anymore today because of all the recovery regulations.
“The video is only explaining this procedure but not showing this process. ”
That’s all you need to know for this type of recovery. With R600a, you don’t need to recover anymore.
““If using a dial a charge “”heat”” it up to 30 “PSI” higher more than ambient temperature on the gauge”. How does a service technician heat “it” up??? They are showing a pressure gauge when they say “heat it up”. Confused.”
When you go to sealed system school or actually start doing sealed, you’ll use a digital scale instead of dial a gauge.
““be extremely careful not to touch the tank or the main valve while dumping the charge…..why? ”
What happens to the refrigerant when you dump a charge? It’s vaporizing (read: boiling) as it changes from liquid to vapor. As it does this, it sucks up vast amounts of energy from everything near it, including your hand. Same thing that happens inside an evaporator. So it frosts up and gets super cold.
” “First to start dumping the charge they show opening the valve on the charging tank. What about the charge valve port on the diaphragm does that need to be opened? What state is the charge port. Is it already open? Doesn’t mention anything about the charge port on the manifold. It then says “open ONLY the high side valve on the diaphragm and dump the measured charged through the high side””
Read the last part of what you wrote: “dump the measured charged through the high side.” How can the refrigerant charge get into the sealed system if the charging valve isn’t open?
“MST course referencing gauges and types of gauges? ”
The gauges don’t make the tech– the tech makes the gauges. Look around on Amazon and you’ll see you can spend big bucks on gauges. The reality is that the $40 set of analog gauges will work just as well as the $300 bluetooth digital gauges.
““If digital scales are used” What are the alternatives just dial gauges instead of digital weight gauges? Is digital weight more precise and preferred measuring system instead of dial gauges? Does it not matter just personal preference?”
Digital is the way to for measuring charge. You’ll especially need it for R600a systems where you weigh out the charge in GRAMS not OUNCES.
“There is no time mentioned “as soon as it hits 500 microns” all finished? Does it take 30 minutes as well to pull the system down to 500 microns or less? How long does it usually take, ”
The length of time of the pump down will vary with how much water has entered the system, as in the case of a low side leak. Could be anywhere from a few minutes to half an hour, sometimes more if the system has had air (and water) in it for a while. Gets all in the oil. It’s a mess. But you hit your 500 microns, close off the valve and watch your micron gauge for 30 minutes. Gotta hold 500 microns for 30 minutes before you charge the system.
“Can a service technician pull a sealed system down so much accidentally collapsing any of the sealed system tubing? Is that something to be concerned about?”
No way, no how. The hoses would collapse way before the metal tubing. Vacuum pumps can’t get anywhere near either event happening.
does it mean the rotor spins at some exact whole number multiple of frequency generated by the inverter?
Yes
if i were to measure the frequencies produced by the inverter what frequencies would i expect to see?
The voltage and frequency will both vary by the type of application (eg., front load washer vs. refrigerator). You’ll need to look in the manufacturer’s service manual for the expected ranges.
Is this explained later in the modules how to determine if the compressor is weak vs a leak?
I think we get into that in the thermodynamics webinar series. To determine abnormal, you have to know what normal is supposed to look like. In a normally operating sealed system, you should see 0 psig (maybe even a slight vacuum) on the low side and about 100 psig on the high side for a R-134a system.
To determine whether you’re dealing with a leak or a weak pump, you need to install valves and gauges. If the system is still holding a refrigerant charge or has had a low side leak, you’ll see an equalized pressure of about 30 psi on the high side and low side. A low side leak can suck air into the system and look similar on your gauges. If the system had a high side leak, there will be very low equalized pressure. You can also run the compressor and note the pressure difference.
In the case of low side leaks, it can be ambiguous to distinguish between a leak and a weak pump. In this case, evacuate and recharge the system then run it and note the pressures on the high and low sides. IF the compressor is working properly, your pressures should be normal. If they’re not– low side pressure too high, high side pressure too low– then you’re dealing with a weak pump.
as i understood a synchronous motor dosent have a start winding which is out of phaze with the main winding so what gives them the torque required to rotate the rotor?
Shaded pole motors don’t have them, either. Both shaded pole motors and synchro motors use permanent magnets in either the rotor or the stator to give the induced magnetic field something to push against and make the rotor spin. The trade off is that they are very low torque and inefficient. You can stop a shaded pole motor shaft with your fingers. Synchro motor only appear to have torque because the output shaft is connected to the motor rotor via a set of gears– a type pf transmission.
With most motors, you test them by running them. Use your cheater cord and hot wire the motor. Both shaded poles and synchros are 120 VAC motors. So cheat away! You should watch this webinar recording for more on that: https://appliantology.org/topic/72423-voltage-voltage-drop-loads-switches-jumpers-cheaters/
Ah, yes, that’s the graphical way of showing you that those switches are ganged together in one location. In this case, water temperature selector switch. Your instinct was correct! All those switches are packaged in a single, physical switch body that screws onto the console and gets a knob attached to it.
Can you give me a timestamp on the video that shows the prongs and dashed lines you’re referring to?
Correctillia!
The R is only real resistance and does not account for reactance. The vectorial sum of resistance plus reactance is called impedance and it uses the symbol Z. Ohms Law still applies but you need to account for the the the total physics of the electron opposition (resistance plus reactance) for the total impedance, Z. So your ohms law equation would be E/Z or sqrtP/Z.
We just need to be aware that’s how reactive components work. We won’t be doing vector calculations in the field. Why? Because we think in terms of WATTS with AC loads, not resistance, and we use our amp clamp instead of our ohm meter.
You’ll need to keep reminding yourself of this because almost all the manufacturer literature today is dumbed down and talks in terms of ohms. They do this because most techs today do not understand even a fraction of what you’re learning in this course, eg., watts, amps, ohms law, impedance, etc. So they have to meet techs where they are. I think they also do it for liability protection because they know most techs are electrically inept and are more likely to shock themselves working on live circuits. So they give specs techs can use on dead circuits (ohms).
I explain that in the video. Start at 10 minutes into the video.
Also, here’s another webinar recording you should watch on the Ten Step Tango and the Timer Chart Cha-Cha: https://appliantology.org/topic/70571-troubleshooting-with-timing-charts-and-schematics-ten-step-tango™-and-timer-chart-ch-cha™/
on you last lesson video there are 2 loads in series one being the evaporator fan meaning that the current should and would be the same for both the def heater and the eveporator fan motor so if i put my ampmeter clamp to measure the current on different points in the circuit i would read the same amount of amps since its supposed to be equal at all points eventough one of them is non ohmic load m i right?
Yes. In a series circuit, the amps are the same at every point in the circuit regardless of the type of load.
secondly how can i calculate voltage drops across them in this case(since one of them is non homic and i cant employ equations that have R found in them)?
In that example in the webinar recording in the lesson, you should have seen that the defrost heater is essentially acting as a wire because it’s resistance relative to the evaporator fan motor is orders of magnitude less (4,000 ohms vs. 12 ohms). That’s the concept I was showing there. That means we can ignore defrost heater for troubleshooting purposes (unless it is actually open). So the evap fan motor is said to be the controlling load because its resistance is so much higher that it controls the current in the circuit. Accordingly, it is still getting virtually all of its rated power supply. Close enough that we ignore the effects of the heater.
The wattage for the evap fan motor will be stamped on the motor itself and also shown in the spec block on the tech sheet. Here again, we don’t bother calculating the resistance of the fan motor (which is also given on the tech sheet, by the way). We know the wattage, so then use the voltage supply along with the fan’s wattage rating to calculate the expected amp reading. We make our amp reading and compare.
Or, even easier, simply look/listen to see if the fan motor is actually running with voltage applied to the circuit! If the fan motor is running, the circuit is working correctly.
Don’t get hung up on non-ohmic loads. Just be aware that that’s a thing and, because of that, we don’t us ohms to make diagnostic conclusions about AC loads. Similarly, don’t fixate on resistance with AC loads. Think in terms of watts.
so if a washer is fitted with an AC asynchronous moter ,when its in the wash cycle it spins at a certian speed and after the drain it goes into spin cycle which is faster than wash in other words the motor will rotate much faster in spin cycle than wash,so how does the motor carry out faster rotation duering spin?
120 VAC asynchronous running on a 60 Hz power motors will always spin at the same speed, 3600 RPM, regardless of direction of rotation. It is a limitation of their inherent design and construction. The RPM speed reduction or increase AT THE DRUM is changed by the transmission. These are old skool machines. Newer machines will use different motors, such as BLDC motors, which can easily be controlled by an inverter to run at different RPMs, including gradual ramp up in speed, thus eliminating the need for a transmission.
another questions that came up are how does the vfd system change the direction of the rotation? does inverter board open and close the IGBT’S in reverse order than what you showed?
Yep. Control the direction of rotation of that magnetic field and you control the movement of the rotor shaft, speed and direction of rotation.
second i know what the term shorted mean when wires are involved,short to ground etc… but when you said a traic is shorted what exactly do you mean by that ? and why when a traic or diod is shorted they will constanly let current thruogh to the other side?
In the context of a specific component like a triac or a capacitor, a failure condition is “internally shorted.” For a triac, this means the PN junction between Anode 1 and Anode 2 has gone low resistance in both directions of current (electron) movement. So the triac no longer acts like a switch but more like a wire, letting electrons come and go in either direction.
Here’s a good article on triac operation for appliance techs that you should read: https://appliantology.org/blogs/entry/953-triac-operation-for-appliance-techs/
The phase shift of the temporary phase is done on-the-fly at the moment of start by the motor’s start winding. In the case of a capacitor start motor, the capacitor increases the phase angle of the temporary second phase. As soon as the motor’s rotor starts rotating, the start winding and start capacitor are taken out of the circuit by the start device or relay. In the case of a capacitor start-capacitor run motor, two capacitors are used: the start capacitor does the increased phase shift for starting– same drill; the run capacitor helps smooth out the back EMF produced by the motor’s run winding so the motor runs more smoothly and uses slightly less power.
i enjoyably watched your lesson about psc motor but one thing i didnt realy got is how the capacitor make one phaze shifted ?
Watch the first part of the video again several times. This is explained without using math.
does the capacitor fulfill the same function on an ordinary run-of-the-mill AC ASYNCHRONOUS motor?does it do the same job?
Yes.
secondly is ther any formula to work out by how many degrees the phaze is shifted by a capacitor? i know these formula 1/2×3.14xFxC has it got somthing to do with the shifted phaze?
There are several formulas. This gets into higher math involving LC circuits, vectors, and trigonometry that is beyond the scope of this course. As a tech, you will not be doing these calculations– you only need know what these capacitors do and how they affect motor operation. In other words, you will not be doing engineering calculations on sizing start and run capacitors.
In general, algorithms can be either mechanical or software. For some things, the manufacturer has to tell you about algorithms that may affect operation and troubleshooting. This can be done verbally with descriptions, or by giving pinout voltages on a board, or by giving you a timer chart in the case of a mechanical algorithm. Other times, you can determine by deduction based on your understanding of technology and circuits. This post at Appliantology has a good explanation and examples: https://appliantology.org/blogs/entry/1106-control-board-troubleshooting-inputs-outputs-and-algorithms/
A quick example would be a computer controlled refrigerator that’s not defrosting. You test amps on the defrost circuit and they’re in spec. Failed computer? Not necessarily! If the evaporator thermistor is out of spec and feeding bad information to the computer, then the computer may never initiate defrost cycle. Knowing about this algorithm, your next troubleshooting step is to text the evaporator thermistor to see if it’s in spec.
This post has another example: https://appliantology.org/blogs/entry/1209-samsung-refrigerator-ice-dispenser-opening-and-closing-repeatedly-where-do-you-begin/
This webinar recording goes into troubleshooting computer controlled appliances in more detail (you’ll need to have your free Appliantology account set up to watch it): https://appliantology.org/topic/56680-webinar-troubleshooting-strategies-for-computer-controlled-appliances/?do=findComment&comment=336620
This webinar recording explains troubleshooting mechanical algorithms using timer charts: https://appliantology.org/topic/70571-troubleshooting-with-timing-charts-and-schematics-ten-step-tango™-and-timer-chart-ch-cha™/
Reading those blog posts and watching the webinar recordings should give you a concrete understanding of how being aware of algorithms can affect troubleshooting.
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