A/C Blower Keeps Rotating But Circuit’s Power off – Test & Repair

In this video, we dive into a common issue that mini-split AC/Air conditioner owners face – a blower fan motor that continues to rotate even when the circuit’s power is turned off. If you’re experiencing this problem, don’t worry! We’re here to help you diagnose and potentially fix the issue. Join us as we walk you through a step-by-step troubleshooting process to identify the root cause of the problem. We’ll explore potential reasons behind the blower’s continuous rotation, such as faulty wiring, control board issues, or a malfunctioning thermostat. Our expert tips and techniques will guide you in conducting various tests to narrow down the possibilities and pinpoint the exact source of the problem. We’ll also provide insights into common signs to look out for and how to interpret them. While we won’t be able to cover specific repairs in this video, we’ll offer recommendations on when it’s best to seek professional assistance and how to communicate the issue effectively to a technician. Safety precautions will also be emphasized throughout the video. If you’re ready to troubleshoot your mini split AC and better understand why the blower keeps rotating even when the power is off, this video is for you. Don’t let this issue disrupt your comfort – let’s get to the bottom of it together!

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I have got this mini split air conditioner circuit  board for repair; I will attach the blower motor   with the circuit board because this blower motor  has a fault. Now I will start this circuit board,  

And let’s see what problem does the blower motor  do. I will power the circuit board. As soon as I   passed electricity through the circuit board. The  blower motor started to rotate. The red light on   the display is glowing. The rest of the display is  not working. The blower motor’s shaft is rotating  

But rotating very slowly. Now I will turn the  circuit board on with the remote. After turning   it on, the green light on the display turned on,  and its display showed a 16-degree temperature on   its seven-segment counter. The blower motor has  also started to rotate at normal speed. The next  

Problem is this: First, I will turn it off,  as I turned it off with the remote. The green   light on the display has turned off. The blower  motor should stop after some time. But it is   continuously working. It will keep working if we  keep the electricity on and do not cut the power  

From the circuit board. The vibration inside the  motor is also a lot while rotating. As I turn on   the circuit board with the remote, the vibration  in this blower motor vanishes. I will have to   wait for a few seconds. As soon as the circuit  supplies power to this blower motor. The vibration  

From this blower motor will vanish. It is still  vibrating. I can feel it while holding this blower   in my hands. I will turn this circuit off with the  remote because it does not stop vibrating. I will  

Remove the electric plug and let’s try to fix this  problem. This circuit board is of a non-inverter   mini split air conditioner. And is from an unknown  brand. The problem I told you about earlier,   we will learn to fix it together and why this  problem is caused in these circuit boards. I  

Can show you this just by replacing a faulty  component in this circuit board, and the work   will be finished. This video will also end.  This way, you will not be able to learn how   this problem is caused. You will only get to know  what faulty part I changed in this circuit board,  

But you won’t be able to learn this as if a  different circuit board with a different design   is handed over to you for repair. Then you will  be stuck saying that I don’t understand how to fix  

It. I have already made videos on the connections  of this blower motor, which will be linked at the   end of this video. The connector of the blower  motor on the circuit has three pins. Two pins are  

The common and run where the line and neutral are  attached. The pin in the center of the connector   terminal is the common point. The pin on the left  is the run point, which is attached to the neutral  

Pin. A capacitor is also installed with it. The  pin on the right is the start point. I have now   installed the multimeter with the circuit board to  test what the problem is with this circuit board.   I have attached the multimeter probes with  the common and the run pins. I will pass the  

Electricity through the circuit board. The circuit  board has powered on. Red light has started to   glow. The blower motor shaft is rotating slowly.  The voltage coming out from the blower motor is   146 AC volts. This means that the triac of this  circuit board has leakage in it. Due to this,  

Low voltages pass through the blower motor before  it is turned on with the remote. And this is the   reason it’s vibrating. I will now turn it on  with the remote. The voltages instantly reached   a maximum of 205 volts. And the speed of the motor  also increased. The voltage has decreased to 186  

Volts. This means the triac is not fully triggered  to let the maximum voltage pass through the blower   motor connector. I will increase the speed of  the blower motor with the remote. Let’s see if   the speed of the blower motor increases. The  blower motor is still vibrating a lot, and the  

Reason behind this vibration is the low voltages  that are passing through it. I have set it to high   speed. But the voltages are not increasing. Now  let’s talk about what a triac is. The symbol of  

The triac is something like this. Three pins are  in the triac. The name of the first pin is t-one,   the second is t-two. And one of the pins is the  gate pin. The gate is triggered with voltages,  

And after that, when it opens up. Then this triac  works as a switch. Whether you pass electricity   from t1 to t2 or t2 to t1, you can make any  one of these pins the input and the output.  

Low voltages will pass through the gate pin to  trigger it. The gate will open up. The t1 and   t2 will start conducting electricity through them.  I will now further tell you what else the problem   this circuit board could have. What is the other  function than the triac? All the circuit boards  

That are based on the transformers have no SMPS.  The high circuit section of these circuit boards   is completely isolated from the low voltages.  Minor or few problems could occur on the low   circuit side. Now, this circuit board is designed  in such a way. That has caused this blower motor  

Problem. In this circuit board design, you have  to attach the live and neutral wires accurately.   If you installed the neutral wire in place of the  live and the live wire in place of the neutral,   then such a problem will be made in this circuit  board. The triac is installed here in the circuit  

Board. Let me zoom into it. To show what its  number is. Its number is bt131-6. If I now   talk about the circuit around the triac. This  complete circuit that I am pointing towards is   the circuit that operates the blower motor.  I will tell you how this circuit works. This  

Circuit is operated through this optocoupler. It  is used for the isolation between the low and the   high voltages and is also used to operate this  blower circuit in this PCB. This optocoupler is   controlled through this Darlington array and is  commonly known as uln2003. This microcontroller  

Controls this uln2003. The circuit is working  in such a sequence. Now let me explain why I   said that the live and neutral connection on this  circuit board should be properly attached because,   in this design, neutral is assigned to the gate  of the triac. The positive electricity crosses  

Through the t1 and t2. Let me show you. This track  is a positive connection. A fuse is installed with   it. This track is moving and connected with the  triac terminal one or two. This is its input. The  

Output is attached with this second pin of the  triac. This pin of the triac is the gate. The   rest of the circuit around the triac is designed  to trigger and open the gate. But the negative  

Supply is given to the gate of this triac. Let me  explain how. This resistor is attached here, with   the emitter of the optocoupler. And move towards  the collector. It happens when the emitting diode   turns on in the optocoupler. The Darlington array  passes signals to the optocoupler. The emitting  

Diode turns on and started to glow. The transistor  on the opposite pins turns on. The voltages then   start to pass from the emitter to the collector.  A max of zero point 4 volts is given. Which makes  

The gate of the triac open. The switch turns on  and starts to conduct electricity between the t1   and the t2. This circuit board has been fixed now.  I will tell you what I did in it. first I will  

Show you how it works now. I have powered it on.  See, the motor is not vibrating. The shaft is not   rotating. I will turn it on with the remote. The  motor will start to rotate in a while. The motor  

Has started to rotate. It has no vibration now.  I have replaced the triac with a new one. I told   you at the start that the triac has a leakage. The  triac leakage caused this problem. I am tired now,  

And I run on coffee. So buy it for me on  Patreon. Click the link on the screen to   visit. . Click on the left or right thumbnail to  watch the next videos. And Subscribe. Thank you.