Blower Fan/Motor Current Does What!? Correcting A Statement I Made - Includes PROOF!
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- เผยแพร่เมื่อ 6 ต.ค. 2024
- Part 1 Video - • Blower Motor Fan Only ...
In this video, we show you what really happens when you restrict airflow to the blower fan/motor. Thanks for watching!
Just like fuel pumps, inlet restriction= less current, higher rpm. Outlet restriction= higher current, lower rpm.
Kudos for standing on the side of accuracy and truth!
This is a little different. Outlet restriction = lower current and the motor whiz bangs over. That's why it sounds like its working harder like a restricted vacuum cleaner. Higher RPM's.
Truth and accuracy are key. Thanks for watching and commenting guys!
Mike Becker, Senior Instructor
Super Mario - I definitely respect your knowledge and experience
Does an outlet restriction cause higher current in a fuel pump? I guess my assumption has always been that less flow (restriction) = less work on the pump = less current draw.
Both an inlet & outlet restriction cause a decrease in air flow rate. A fan is a type of centrifugal pump. A characteristic of centrifugal pumps is that (in general) decreased flow rate means less work is done, therefore the current will decrease with either a suction or discharge restriction.
Good job Mike. It takes a great person to own their mistake and make it right.
Thanks man, appreciate it!
Mike Becker, Senior Instructor
wow, an extremely conscientious auto technician thanks man.I don't think we get a lot of poor technical advice because there are a lot of dishonest people in that domain, rather because it is a very complicated subject and good technical training is lacking especially when it comes to upgrading.
Congratulations on your commitment to presenting accurate information. Those who question such misconceptions are usually labeled "haters" or "fascist pedants" by TH-camrs. You chose to place truth above ego. Thank you.
Hey Fascist Pedant, thank you very much. Truth above ego always!
Mike Becker, Senior Instructor
Excellent nice video good Box.for explaining how heater blowers work.
Hey Nigel, thanks!
Mike Becker, Senior Instructor
Nice video Mike! Thanks for caring enough about what you do to make a correction and set up a demo to explain. Praying for you and your family
Hey Frank, thanks for taking the time to comment :) Appreciate you watching!
Mike Becker, Senior Instructor
glad you corrected the airflow limiting current draw issue. I learned that years ago, but I've been into electronics and electrical since a young child.
cabin filter restriction does cause less airflow which can make the resistor block and motor overheat, since they're also air cooled!
good videos overall ;)
Hey Throttle Bottle, thanks for watching and commenting!!!
Mike Becker, Senior Instructor
Really appreciate you taking the time to not only address the (imho very common) misconception of increased resistance = increased amperage ( in a centrifugal style).
Quite enlightening.
Bring back your wire connection experiment please! I've seen several tech induced pigtail failures in the last week due to butt connectors on the underside. Would love to see a test set that was "salted" with current running through it.
Hey Matthew, thank you very much for watching and commenting! I did a follow-up video where I ran 20(?) amps through it if I remember right...here's a link for you. th-cam.com/video/gKx_8-Z5sBo/w-d-xo.html
Mike Becker, Senior Instructor
Years back my grandad challenged my thinking with a squirrel cage shop fan as an example. It was probably the Sanford & Sons 1000 model. Of course I was wrong. Lol. Many times I’ve looked back on that experience with fondness, it was great lesson learned.
The old man had many years of experience on his side not to mention humility that most young guys like myself lack.
Thanks. Always appreciate your easy to understand style.
Hey Kevin, thanks for watching! I too have lessons like that. I also look back on them fondly and smile. Hopefully I'll be able to teach some of them to my boys.
Mike Becker, Senior Instructor
GoTech - not to be too personal, but you’re raising kids and that’s a job many of us are learning as we go. Just like you’re teaching all of us automotive wisdom..... here’s a gold nugget of parenting wisdom “time invested is never time wasted”. Make every moment count.
Thanks for that Kevin, i'll keep it in mind :)
Mike Becker, Senior Instructor
Very few people can admit a mistake nice explanation
Hi Mike!
The most common failure that can appear in HVAC system is situation when we are starting car when HVAC is set on 1-st position and blower motor have little hard to rotate. The motor don't turn at all and current which flow by blower resistor can overheat it (no flow of air).
User don't think about it and malfunction is ready.
Greeting from Poland.
Roman.
slightly true, as an already bad blower can be in stall out and draw high current.
Hey Rmx2rmx, thanks for watching and sharing! Stay safe over there in Poland!
Mike Becker, Senior Instructor
Mike keep up the good work and getting back to me NOW 1 more test put your temp probe on the motor no filter and plugged filter like to see how the bearings take up the heat when filter is plugged CHEERS
Ohh temp would have been fun to capture for sure...next time!
Mike Becker, Senior Instructor
The cabin air filter between the blower motor and evaporator helps keep tiny copper partials from the blower motor brushes and bushings out of the evaporator. Copper in the aluminum fins of the evaporator could cause electrolysis if moisture is on the outside of evaporator. At least that is the story I heard. Great Video!
Great Video !! You are the Best - wounderful Contraption !!! Putting out this Video really shows that Prooving things even if you were not right first and that you really care about the Information you release !! Big THUMBS UP !!!
Hey Chrisi1909, thank you very much! I'm all about the truth and accuracy of information. I really appreciate the kind words.
Mike Becker, Senior Instructor
All the guys are using the HVAC 12000 now days.... your so behind the times Mike 🤨🥱
Hey Eric, you know it's just like computers...the second you buy them it's out of date. The HVAC 10000 didn't have the "update" option that may be found on the newer models ;)
Mike Becker, Senior Instructor
HVAC 12000 .... not a sponsor
At least it's not made in China.
*you're
I'm sorry, I had to. 😁🧡
Great vid Mike very nice demo, really appreciate the vids you’re putting out during this time. Hope you and the family are staying safe
Hey Amyn, thanks for watching! We're doing everything we can to stay safe, hope you and yours are as well!
Mike Becker, Senior Instructor
Excelente experimento, normalmente no nos tomamos el tiempo para hacer estos experimentos, pero son muy didácticos. GRACIAS
Gracias
Outstanding demonstration Mike. Thanks!
Thanks man!
Mike Becker, Senior Instructor
Hey Mike, I've been bested by my preconceptions many times. Happens to the best of us.
Hey Bgregg55, ugh I hate it when it happens...but hey, that's life!
Mike Becker, Senior Instructor
well done mike! the old chevy trucks had the filter after the blower motor stay safe!
Hey Scuba422123, thanks for watching! You stay safe as well!
Mike Becker, Senior Instructor
Good update Mike. Continued success with the new video series!
Hope you and your family are all well.
Hey Mike, thank you very much! We're doing well here, hope you are as well!
Mike Becker, Senior Instructor
Thank you Mike. Have a blessed and safe week to you and your family.
Thank you so much Billy, you as well!
Mike Becker, Senior Instructor
@@GoTechTraining Thank you Mike. If you ever get a chance to work on a Honda or Acura with a blower motor power transistor, please test and record the power transistor control wire voltage signal with connector unplugged and plugged in and back probed. There are a few videos on TH-cam about the power transistor but nobody has tested this control voltage with connector unplugged and plugged in and back probed to see what known good AC Control Unit sends down that wire to the power transistor.
Sounds good Billy, will do!
Mike Becker, Senior Instructor
With restricted airflow the current goes down due to lower loading because the air in the blower case begins to spin with the impeller.
In the case of a restricted vacuum cleaner, being a series motor the RPMs increase significantly as the current through the field coil also gets weaker with lower load, but the blower motor has a permanent magnet field so the RPMs do not increase that much.
Mechanical loading increase due to tight bushings (sleeve bearings) on the motor causes both increased current and reduced airflow on the lower speed settings, a disaster for the resistor but I have also had a few resistors fail for just a dirty filter, the motor itself has been fine.
Any failed resistor, the motor is tested and the filter replaced as a matter of course.
On some vehicles, with the air distribution control set to face vents only and all face vents turned off with their own control, the system has a 100% restriction. This is a reasonably common occurrence, look at the control settings when a vehicle comes in!
That will definitelycause the resistor to burn out even with a perfectly good motor and filter!
Hey Simon, thanks for watching and for the lengthy comment. Appreciate all the info!
Mike Becker, Senior Instructor
Like yourself and Scannerdanner (keeps his mistakes in his videos), it's damn good to see you not remove your mistake, but to amend it!
Mike thanks very good example
Hey David, thanks for watching!
Mike Becker, Senior Instructor
Good correction on the previous video. I just watched the previous video a few minutes ago and was wondering what the correction would be until I heard the oops moment. In regard to minute 5:40 where the balloon (and you can keep your secret save from your son with me) is being drawn toward your nice experimental creation, you will find the pressure differential "favors" the outlet side as opposed to the inlet side of the system, thus creating a situation where the higher pressure side is now turned 180° at the impeller and directing air flow opposite the normal direction.
Keep up the great work!
Hey Chad, thanks for watching! Makes sense why the "borrowed" balloon was drawn in. Thanks for watching.
Mike Becker, Senior Instructor
You Right for the wrong reason, But you are still Right, First Class!
Right, wrong, as long as the info is accurate that's all I care about :) Thanks for watching Rollen!
Mike Becker, Senior Instructor
If you still have the rig set up you should blow a leaf blower into the inlet. That's kind of neat too.
A hmm give it more and and see what it does, interesting thought!
Mike Becker, Senior Instructor
You're a class act, Mike! Thanks for clearing that up! I thought I was going crazy and had my thinking backwards, lol. I forget so much these days that I rarely call anyone out on what I think is a mistake, because 9.9 times out of 10, I'M the one that's wrong, lol.
Thanks for all the effort in building the HVAC 10k! Great demo. 👍🍻
Hey Smitty, thanks man! Yeh, sorry to screw you up on that one. I'll build you one if you'd like. $799.99 plus tax and shipping ;)
Mike Becker, Senior Instructor
GoTech - No worries man. Oh, and I’ll take 6 of those at that price.😁
Sounds good, email me that CC# i'll get right on it!!! :)
Mike Becker, Senior Instructor
GoTech 😁😁
Wow learned something new today thanks
Hey Paul, thanks for watching! Glad the video was useful for you!
Mike Becker, Senior Instructor
Hey Mike!Great demonstration!
Thanks Ismar!
Mike Becker, Senior Instructor
I have noticed this same effect with my vacuum cleaner. When you completely block the intake the motor sounds like it speeds up. There is a point of restriction that appears to load the motor more that it is when completely unrestricted but when completely restricted the motor speeds up. I have always found this interesting and tried to figure out why. My guess was that the high vacume causes the air to be less dense and that would make the impeller see less resistance to turn. Not sure if this same thing happens when a fluid is being used by a similar centrifugal pump. Not sure you were completely wrong about the restricted filter. I think a partial restricted filter will cause the motor to see a load increase.
Could we do some actual testing to determine the original failure (blown resistor). I typically like to use HVAC diagrams to help teach the younger up and coming techs. Its good system, for ohms, voltage drop and current testing. Even using the amp clamp to try and determine actual motor rpm. Food for thought....
Hey Josh, sure normally we would. These videos are intended to be short quick hits. I have other videos already showing blower motor testing. Yes, wiring diagram, voltage drop and current testing are all great on these things!
Mike Becker, Senior Instructor
Blower works just like a battery. When you have resistance in the path you have a reduction in current and CFM. But since fan needs air to move it gets air from the chamber that surrends it. So as the air leaves the fan's fin it forced into blower again so you almost have a vacume at outlet and you have a turbulance in chamber.
Thanks for watching and the clarification Mohamad Reza Enayati!
Mike Becker, Senior Instructor
no air no work. lots of trucks have multiple blower motors and often they run in different directions. because of this the squirrel cages are reverse rotation too. found out if you put a reversed squirrel cage on it will blow a little but not a lot and the amp draw was way down. also there are modules that act as resistors that use thermisters. and i have seen these that look identicle to a resister package
Hey Richard, thanks for watching! I powered this set-up backwards and the motor spun like mad but didn't create hardly any airflow....therefore little current. Same principle I believe.
Mike Becker, Senior Instructor
Mike, thank you for correcting that enjoyable to watch. cheeeers
Hey J Georges, thanks!!! Glad you found it enjoyable :)
Mike Becker, Senior Instructor
Great content... I dont think the amp draw on the fan is quite as important as maintaining air flow over the resistor... Ive known a few blow either because the cabin filter was dirty or the inlet vents on the scuttle panal were blocked with leaves n debris...
I was shocked though that the amps used actualy went down when the air supply was blocked. Simular to i expect a engine that cranks faster when the air intake is shut off.As it has no air to compress it dosent work as hard....
Thank you very much! Airflow is the real killer here, I agree. Thanks for watching and commenting!
Mike Becker, Senior Instructor
Well done!!
Thank you very much Eli!
Mike Becker, Senior Instructor
it sounds like a restriction before the blower motor creates like a vacuum cabin inside and less drag for the blower fan, not sure why current drops after the blower motor but good experiment
Thanks for watching!
Mike Becker, Senior Instructor
Love it! Great job!
Thanks Che Kelley!
Mike Becker, Senior Instructor
great video!!
Thanks Neil!
Mike Becker, Senior Instructor
Hello 👋 Mike ! Do you have a part # for A/C case ? Jk thank you for taking the time to build the Case . Means a lot to money of us.
Hey David! haha yeh I think I can find a part number somewhere...hang on i'll make it up ;)
Mike Becker, Senior Instructor
good video, i would have expected higher current
Hey Henry, yep you're not alone on that one! Thanks for watching.
Mike Becker, Senior Instructor
So if V=IR, assuming you still measure the same voltage going to the blower motor, if it's consuming less current (during a restriction), doesn't that mean that the internal resistance of the blower motor goes UP in order to keep the equation true in the great and wonderful universe, i.e. laws of electrical physics? Would this contribute to the early failure of a blower motor? I'm assuming that it's temperature goes up, not just because of lack of airflow, but if it's internal resistance has gone up, that usually generates more heat as well, right? Interesting experiment dude. I got the recommendation from South Main Auto youtuber to come check you out...boy am I glad I did and you got yourself a new subscriber!
Hey Mark, That would make perfect sense in the world of electrical physics! I'm glad you've found us, thanks for watching and welcome :)
Mike Becker, Senior Instructor
I wonder where resistors are mounted. If they are down stream from blower. They could be increase resistants as geting hotter when less air flow thruogh them. That make less current to blower motor.
Hey Cu Lan, typically the resistor is mounted down stream from the blower. Very true points!
Mike Becker, Senior Instructor
Because resistors connect in series with blower the hotter the more resistants the less current to motor.
kinda backwards of what i expected, wonder if it would be different for a blade type fan rather than a cage? great video!
Hey DoctorSherwood, hmm great question. May need to take a look at that at some point too!
Mike Becker, Senior Instructor
I can see why you made that assumption, many motors draw more current under load. Your thoughts about the higher risk of overheating because of inadequate air cooling are also completely reasonable. I wonder what is special about the blower motor.
Hey Spelunkerd, hope all is well! Thanks for watching. I'm used to thinking about fluid flow I guess...airflows very different. That's where I went wrong I think. Either way, the proof is in the scope :)
Mike Becker, Senior Instructor
All motors draw more current under load. The explanation in this case lies in the fact that the motor drives a centrifugal blower. The less air it receives, the less mass it must accelerate, the less load on the motor. The motor draws less current because it turns faster because of the reduced load.
Good explanation! :)
Mike Becker, Senior Instructor
@@fascistpedant758 What an inspiring post (and video). I spent the morning reading about the centrifugal fan, Wikipedia have a detailed article. Thank you Faschist Pedant.
Electric motors that drive centrifugal pumps also behave like this. A pump not moving much fluid will draw less amps than a pump at full load. In power plants we actually use ammeters to measure a fan and pump load/work being done.
Fixing heat issues in 94 Chevy truck
That's that myth busted then. Nice work.
Ohh I need one of those signs, like from that mythbuster TV show!
Mike Becker, Senior Instructor
Mike All's Good thxs again....
Thanks for watching Ed!
Mike Becker, Senior Instructor
I am not sure I agree with you. Its a dc motor. When the filter is blocked the amps come down because the fans rpm has increased creating more counter electro magnetic force. Because of this the amps come down but the fan is spinning faster so working harder. What do you think?
Great video Mike and looks like you shop a lot on Rock Auto 😎
Hey Bob, thanks man! Yeh, I guess I do. Typically price is more of a factor than speed for a lot of stuff I work on.
Mike Becker, Senior Instructor
@@GoTechTraining Same here & save a lot of $$ and also get OEM parts at AM prices!
Hello, would you like to try using the emergency jump starter to start a dead battery of your car?
I think I have more RockAuto magnets on my cabinet. Lol
Forward curve
Guys i have a problem with my 06 suburban. Sometimes when i turn on the a/c or the heater the blower fan wont turn on or it will turn on and will shut off but turn on after a bit. If i turn off the truck and turn it back on the blower will work again.
Hey Msia40004, sounds almost like an intermittent connection. Those vehicles were somewhat common to melt the connector on the switch if I remember right.
Mike Becker, Senior Instructor
my only question would be what happens to current when a motor is left to run for a long period of time. Would the motor need the (unclogged) airflow to keep it cool? If this airflow is then compromised, would the efficiency of the motor decrease leading to an increased draw? I just know that of the motors I've replaced, when they heat up they loose efficiency and I think the current draw is increased.
I believe the temp increases due to lack of airflow and I think this could have a negative effect on the bearings themselves within the motor. Either way, plugged airflow is bad ;) The system would probably be better off with no filters than plugged ones.
Mike Becker, Senior Instructor
Moved my reply onto the main thread
Is that what is called cavitation ?
Hey Bigcliffe, cavitation usually relates to liquid right? Can it be related to air movement?
Mike Becker, Senior Instructor
@@GoTechTraining In the airline industry we have a similar thing in a jet engine it is sometimes related to. Something that causes a surge. It is when the blade speed goes beyond the speed the air can pass through between them. It is normally heard as a very loud bang. Compressor stall.
Sounds really interesting. I've always enjoyed airplanes but I know almost nothing about them.
Mike Becker, Senior Instructor
👍👍
Hey Sm Ms, thanks!
Mike Becker, Senior Instructor
Blower motor does not work what can be the problem ( my relay“click” noise can be heard from the blower motor relay. when I moved in position 4 )
Hey, you're either missing power, ground, or the motor is toast. Try a test light across the connector to check for your power/ground.
Mike Becker, Senior Instructor
@@GoTechTraining I have 12 Volts both the power and Ground of the blower motor and (The Blower does not work on any speed again ) thanks
That’s confusing, reducing the speed (RPM) of a DC motor normally increases it’s current draw. Think of a slow turning starter motor due to seized engine. So why did a reduction in speed lower it’s current draw? I’d like to see if the RPM differs with and without the restriction on the motor.
Hey John, I the current decreased because there wasn't any air to push. Therefore the motor didn't have to work as hard.
Mike Becker, Senior Instructor
i like the video thanks
Hey Luther60, thanks!!!
Mike Becker, Senior Instructor
Congratulation, very good class, Thank. Se you next video.
Thank you very much Manuel!
Mike Becker, Senior Instructor
Could you measure the duty cycle? And voltage?
I like your videos but you still need "Dancing Girls" 💃💃
Hey Gregory, on this example the duty cycle would have been 100% because I was runing the blower on high speed. Voltage will be battery voltage again, high speed.
Mike Becker, Senior Instructor
Ah so I'm going to stop recommending a cabin filter change because it works better with a plugged filter...nnnaah...just kidding Mike! 😊
I'm no brain surgeon and I'm definitely not the brightest in this industry, but I'm willing to bet a couple hundred with anyone that a motor with a plugged filter will go bad faster than a motor with a clean one. How about an experiment Mike? 😁 I know it would probably be hard to set up and it would take too long until they fail...
Hey Nick, makes sense to me lol! That sounds like a long term experiment. I don't think I have that kinda time...and I'm almost out of plywood ahahah!
Mike Becker, Senior Instructor
I'd kill to have easy access to my cabin filter. God I hate Nissan Rogues!
Hmm not sure i've ever done one on a Rogue, that bad huh?!
Mike Becker, Senior Instructor
Now what about the motor speed?
The motor speed will increase when air is restricted as blower is not pushing air by volume hence the reduction in amps think of it like a fuel pump pumping fuel or not same principle air is weight hope that helps
@@terminaldiagnostics5576 Hi it was a kind of tongue in cheek comment, I was hoping to see it proved using the Pico waveform just out of interest Maybe Mike will post the file.
Hey Niall, thanks for watching guys.I didn't plan on sharing motor speed. Had I done a longer class I would have probably.
Mike Becker, Senior Instructor
Any one heard of "Cavitation"?
Can cavitation apply to air or only liquid?
Mike Becker, Senior Instructor
@@GoTechTraining Don't know, but a similar effect happens when you block the airflow on a vacuum. loss of air flow, and the RPM's pickup as if running in free space. Or the over-rev roar you hear from an outboard motor, when the pilot cranks of an oblique turn from near stand still.
@@plowe6751 Blimey,Yah, sort of!
i dont care about this but youtube keeps on and on and on and on insisting i watch it despite hitting the not interested button and dont show channel button.
this had better be good
Well, how was it?!
Mike Becker, Senior Instructor
Hope krankin kogs got his moneys worth.
You might have to send h8m a refund.
this would be a good test to do with plastic bag on engine air box when rodents build nests use scantool compare reading feul trims
Hey Wesley, sure as long as the engine doesn't die :)
Mike Becker, Senior Instructor
Haters gonna hate
There's no avoiding it :)
Mike Becker, Senior Instructor