PSC motor operation with and without capacitor

This one covers what happens when the PSC motor run capacitor is bypassed. This video is part of the heating and cooling series of training videos made to accompany my websites: www.graycoolingman.com and www.grayfurnaceman.com to pass on what I have learned in many years of service and repair. If you have suggestions or comments they are welcome.
If you are a homeowner looking to repair your own appliance, understand that the voltages can be lethal, the fuels are highly flammable and high pressures are used. Know your limits.

[@snerby141989]

Thanks for taking the time to demonstrate! I'll wait 12 more hours in this heat without bypassing my blower's capacitor until the replacement comes in

[@haroldlanglois8986]

The best explanation of many MANY videos I have researched, thank you!

[@randybarnhart6976]

Great video and explanation. I am working on an attic exhaust fan and have removed the VIM capacitor and I'm testing it. Your video helped me understand the role of the capacitor in relation to the fan. I think I have a bad capacitor.

[@ruenjou]

Love to see people actually were experimenting like Mr GFM did

[@bababooey7576]

My co worker and I this past tuesday, just replaced the two original capacitors on my 1983 Keeprite Flextemp air conditioner...both were still working, but the one for the compressor had lots of oil sitting on top of it and it had for quite a few years...This is the first work this air conditioner has ever had and it was preventative maintenance...I just had the feeling, from all the videos Ive seen on youtube, and reading, that it was a matter of time before both caps went...the fellow hooked up his meter to them and they were still functioning perfectly...the oil on them kind of told me it was a ticking time bomb...barring a leak in the system, the air conditioner should be good to go for years. (i'm thinking) They don't make things like this anymore....I bet I could have the house down to below 65 on a hot day with this unit...Love your videos and have come here for reference many times...(not in the business, but keen interest and have tuned up so much around my house regarding hvac)

[@1tom35]

This little video was a good eye opener for me

[@SuperDirtyred1]

just bought a Century DL001 GE Replacement 1/4 HP Direct Drive Blower Motor 115 Volt 3.5 Amp / did not no it needed a cap , sometimes running forward/backwards, was just about ready to start a return/Ebay until I say your U.T. post Thanks a lot for saving me the big hassle.

[@grayfurnaceman]

Welcome GFM

[@brentaudi9354]

Thanks for the demonstration! It all makes sense!

[@Forge5894]

GFM, excellent demo! It is a HUGE help to be able to see the meter readings as you explain the theory. Thank you!

[@Sixta16]

Theory not as right, didn't show what happens with the cap disconnected. (won't start by itself, will start if pushed) Showing what shorted cap does is a nonsense.

[@rmwaseem]

Thanks for very clear explanations on the use of Cap.To make it more interesting if you had a switch or relay that closes when power is DISCONETED and just shorts the motor wiring together (line and neutral) then you will see that you have applied counter EMF to the motors winding which is opposite to its rotation which will cause a sudden brake and stop the motor immediately!! There are many motors that we use today that uses the braking, re-generative power or with resistor banks in parallel to slow the speed of motor ( example: Locomotive miter saws)! I hope this simple motor example is enough for this topic ! and lets not get carried away building something else !

[@protonhead1]

very enlightening, thanks for all your great videos.

[@jeffm2787]

Think 3 phase motor, but two phase. The second phase is from the phase shift caused by the capacitor. Don't mess with the capacitor value unless you have the ability to scope out the two windings to verify the phase angles or have a meter to show the phase relation.

[@DigitalFireIT]

Just wanted to say that this was SO useful, thank you. Helped me a lot.

[@stevenlavimoniere]

great video ..

[@XanCraft21]

Compare this comment to the one from GunnyNinja, there is this old scrap yard by the maintenance place at bardstown city schools. Sometimes I go down there to find old motors. One day I found this one blue-ish induction motor. The shaft still spun good even with the big dent on the side. I did not know how to connect the 5 wires on it, but I knew 2 brown wires had a capacitor. One day I went back and found another one just like it, but it had a great fall off a high place (the hole front cover was busted and the shaft didn't spin). The good thing was it had a capacitor on it, so I took it home and put it on the not busted one, got some alligator clip wires and a plug from an old alarm clock, found a wire grid on the label, did what it said, plugged it in and it worked fine. It could run for 5 minutes and be a bit warm on the side, and it's still running today, strong and fast, but maybe backwards spinning.

[@rickbraden4272]

Thank you for experiment!

[@Enigma758]

Thanks, I needed to bypass the cap just to verify that the motor was working at all. Always remember "ELI the ICE man" is your friend!

[@ronaldcach2779]

Thanks for your experiment. Learned a lot. Thanks Friend.

[@grayfurnaceman]

+Ronald Cach Welcome GFM

[@bigshedideas8663]

Excellent video thanks for your time and sharing just what i wanted to know

[@grayfurnaceman]

Welcome GFM

[@vemlacduong1954]

Thanks for sharing your knowledge.

[@grayfurnaceman]

+quang nguyen Welcome GFM

[@hg2.]

Great to see what happens when it tries to run without the capacitor. It makes one appreciate how well they run 99+% of the time. Thanks for making. Given the state of the world and its idiot politics, one has to come to places like this for relief.

[@grayfurnaceman]

Welcome GFM

[@bbm8873417]

Thanks for sharing your knowledge GFM

[@enriquehernandez4291]

Thank you for uploading this

[@grayfurnaceman]

Welcome GFM

[@russturner6875]

Good video .... always informative !! keep up the great videos

[@MrJimgillnm]

Thank You !

[@A_O-o3p]

great vedio i learned alot from it very great way of explaining keep it up

[@grayfurnaceman]

+Ali Al-Obaidi Thanks for the support. GFM

[@coilsmoke2286]

I learned that sorta 'ringing' or 'wong_wong_wong' sound means capacitor trouble in fan motors. Failing run capacitors can mimic bearing problems when the motor starts then slows way down and that peculiar sound gets louder. You may think the bearings are heating and starting to bind. i guess it is the capacitor heating and changing it's value.

[@grayfurnaceman]

Coil Smoke The way you can tell if it is bearings or a capacitor problem is to shut the motor down. If the "bearing problem" goes away, it could be a capacitor. GFM

[@squidusn71]

@@grayfurnaceman if the capacitor is "worn out" will it slows down the rpm of the motor? If so, that might be the an issue that I'm having. I noticed that my blower output has gotten weaker. I don't hear or notice any indication of bearing wear.

[@grayfurnaceman]

@@squidusn71 Capacitors are usually "go or no go". I would be looking for air flow restrictions. Dirty blower wheel, plugged A/C coil, plugged secondary heat exchanger coil, plugged filter or restrictive ductwork. GFM

[@callmebackfriday2]

I have a 230V A/C fan motor with 3 wires - Brown, Yellow, Black. How can I test it to make sure it works by using the house 110v outlet without the capacity. Thanks for the video.

[@grayfurnaceman]

You can't test a 240 volt motor on 120 volts. GFM

[@callmebackfriday2]

@@grayfurnaceman Thank you for the information. How can I test it just using a multi meter? Thanks again.

[@grayfurnaceman]

@@callmebackfriday2 About all you can do with a multimeter is test for integrity of the windings. Ohmmeter short to ground test, winding continuity.

[@callmebackfriday2]

@@grayfurnaceman Thanks for the information.

[@athishramgulam5695]

Hi Thank you for this video. Please advise, on a jumping castle motor, do I have to replace capacitor with the exact same

[@grayfurnaceman]

The cap must have the same or higher voltage and the strength must be within 10%. GFM

[@kevincalisto4127]

Great video thank you very much

[@ArcanePath360]

Thanks for this. Exactly what I needed to know. I've got 2 motors running on a circuit, which I've hacked to each run independently, but it's still running off one cap, which I'm not sure I've wired up right. A lot of times the 2nd motor won't start and I suspected that I need another cap; one for each motor now.

[@ArcanePath360]

Interestingly, I took away the good motor to see what would happen (so they're not sharing a cap) and the remaining motor still fails to start sometimes, until I hit it. I guess the motor itself is knackered?

[@grayfurnaceman]

Could be the start switch. GFM

[@ArcanePath360]

Start switch? You mean the button I press to turn on? In that case the other motor wouldn't work either

[@grayfurnaceman]

The start switch is inside the motor. GFM

[@ArcanePath360]

AFAIK there is no such thing. At least not with the motors I work with.

[@SteveSam66]

GFM, Excellent video

[@phooesnax]

Good demo. Thanks.

[@Ziji-LetYourSoulShine]

Is there a start winding in the psc motor, itself? Or only in the capacitor? Fan won't kick on. The capacitor was out of spec, so replaced it. It still makes horrible loud buzzing noise and fan will not kick on. I tested the new capacitor, just to be sure. It is good and in spec. I tested resistance from each of the speed wires to common. They all had good readings. (Black, high speed, cool - 3.2 Ω. Blue, med high speed, heat - 4.5 Ω. Yellow, med low speed, park - 5.8 Ω. Red, low speed, park - 9.3 Ω.) (Disconnected them from board before testing) Fan spins freely when pushed by hand. I tested from each brown capacitor wire to common, they both showed resistance. (1st capacitor wire, brown - 9.3 Ω. 2nd capacitor wire, brown - 39.4 Ω) I tried bypassing board and connected black, cool wire that goes to fan, directly to door switch, makes same horrible loud buzzing sound when door switch is depressed and fan does not spin...

[@grayfurnaceman]

Yes, the motor has a start winding. You probably have either worn bearings (dragging on the stator), or a bad winding. GFM

[@anthonycooper5149]

Great video. Thanks buddd

[@thegrayhandyman9964]

Welcome GFM

[@Solracotos]

Will a bad cap cause overdrawing and breaker trip?

[@grayfurnaceman]

It could due to the prime load not starting. GFM

[@jimdavidson5208]

You turned the shaft backward on the no cap test. Possible reason for more noise and current?

[@grayfurnaceman]

You are correct. However, it makes no difference which way the motor turns, the result is the same. GFM

[@YuriSoul2222]

Do PSC motors use "start capacitors" or "run capacitors"? If I have to order a replacement for my PSC motor, which type do I buy? Thanks.

[@grayfurnaceman]

PSC means Permanent Split Capacitor. Emphasis on permanent. Run capacitors are in the circuit all the run time of the motor. They provide a "soft start" and increase efficiency of the motor. When you buy the motor, the model plate on the box will have the specs for the run cap. GFM

[@YuriSoul2222]

@@grayfurnaceman thanks Gray that helps a lot. Because I heard if you try to use a start cap instead of a run cap where needed, it can blow that start capacitor. Cheers sir

[@markharris1683]

What if there is no cap can you wire one in the circuit

[@grayfurnaceman]

No, the motor is not designed for one. GFM

[@jaimehernandez5791]

The purpose of the capacitors in motors is to reduce the VAR power produced by magnetic motors, the VAR are parasites power and is bad for the systems, increase in VAR its mean increase in amp.

[@riverbankhunter5333]

Without capacitor, motor start to run meantime winding insulation start to burn, depend up on motors.

[@johndoe2022]

What will happen if I will remove the capacitor out from my AC compressor, and will turn on my AC on? I mean with open circuit, not putting the the cap terminals together.. will i make any damage?

[@grayfurnaceman]

Generally, the motor will not start. If it starts, it will run at higher than normal amperage. It will damage the motor. GFM

[@johndoe2022]

@@grayfurnaceman Its capacitor only for the compressor, the motor fan have a different cap... Does it make any difference?

[@grayfurnaceman]

@@johndoe2022 Lets back up. Why would you want to remove the capacitor? GFM

[@johndoe2022]

@@grayfurnaceman I took the capacitor out to take it to the store to buy new one. I will come back to the house only more 48 hours. There are another workers there, i told them not to turn the AC on, but im pretty sure they will. So my question is just to know what is the damage the can make by turning it on, despite i told them not to :)

[@grayfurnaceman]

@@johndoe2022 I see the problem. The unit will probably survive. The best solution is to lock out the disconnect. GFM

[@geojor]

good test...

[@hectormarkmunoz]

So basically if you want to determine that you have a bad capacitor you could bypass the capacitor and if runs the cap is bad?

[@grayfurnaceman]

I would not do that. I would check the strength of the cap or just replace it to test. GFM

[@hectormarkmunoz]

grayfurnaceman ok thank you

[@jerryjamify]

I have a carpet blower that runs for ten minutes then shuts off and comes back on, is this a capacitor problem doing this?

[@grayfurnaceman]

First, I would be sure the cooling holes in the motor are open. It could be a capacitor problem. The only way to know is to test the cap or replace it. GFM

[@hg2.]

Thanks much for this! Was looking for it half the afternoon for a 2nd viewing. Am having trouble keeping "capacitors" straight (maybe because people keep calling them "run" capacitors; I wish I'd never heard the term "run capacitor").

[@jr3474]

what happens if you put two capacitors in parallel??

[@grayfurnaceman]

That would make the capacitor too large. The capacitor works by retarding the peak current. An oversized capacitor will increase that retardation. That will damage the windings of the motor. GFM

[@jr3474]

@@grayfurnaceman thanks for your answer and for the video.. nice work!

[@MrMac5150]

Lets do this same video, but this time just disconnect the cap and do NOT connect the two wires together. and lets see the results.

[@FishFind3000]

It won’t run

[@jelipejeringas9203]

It will run, as in writing this comment I have one running just right!

[@samehdarawshi3537]

thanks. is this capacitor considered a run or start capacitor? what is the Micro farad rated for?does it have a governor system that separates capacitor after reaching speed? thanks.

[@electriccar3253]

It is a run cap. MFD varies with motor size. As it is a run cap, it stays in the circuit. GFM

[@samehdarawshi3537]

@@electriccar3253 thanks

[@Mark622111]

Trying to troubleshoot my attic AC blower. The outside compressor works fine but the attic blower won't start. Issue is sometimes it starts sometimes not. Is a hit or miss thing. I'm fairly certain it's the cap but for now don't want to shut the system down to check the cap's micro farads so have the blower running 24/7 in the on setting (Texas in June - August). For now thinking about replacing the cap and board together come fall since I have to be in the attic anyway. Can this wait till fall? I don't want to burn up my AC blower motor.

[@grayfurnaceman]

If your unit has a belt drive motor, the start switch is failing. Means a new motor. If it is a PSC motor, the problem may not be in the motor. You could have a fan relay problem. GFM

[@jayantapalai2893]

Hey today I got a major problem that is motor is not starting , I trip the switch and running the motor it's starting for 4sec and Trip again, after that I trying same types but it's not started. After that I opened the back cover and reset the trip and running but it's not started, I just moved the fan and motor is started/ moving, after that I off the switch and again start it's not started, after moving the blade it's running, I can't understand what's the faulty, capacitor is 200-250mfd only starting capacitor is available this motor... Plz tell me what's the problem is?

[@grayfurnaceman]

The start switch is probably failing to make contact. If so, you will need to replace the motor. GFM

[@heatpumphvac3150]

Well if the cap was bad well even it would work wouldn't it over heat and trip the internal motor protector

[@grayfurnaceman]

heatpump hvac Yes they will. It is interesting to note that different motors react differently. Some will not start, but some will start with overdraw. GFM

[@heatpumphvac3150]

Yeah they will

[@therealstgable]

So eith a PSC Motor. The start and run winding is always energised? What type of Capacitor motors have the capacitor start the motor then drop out abd just have the run winding doibg the rest of the work?

[@grayfurnaceman]

Sam Hargreaves Yes they both are energized. The motor you mean is the capacitor start split phase motor. This one uses a start capacitor of high strength to start the motor, then a centrifugal switch drops the capacitor and the start winding out. Hope this helps.GFM

[@therealstgable]

Thanks! You're awesome.

[@suspectbane4991]

I have a question. To replace a 4 wire motor unmounted cap with a 3 wire motor w/ mounted cap both are 2 speed high & low but replacement has only one line. Can I abandon old cap?

[@grayfurnaceman]

Yes. GFM

[@droquesteni]

U got a subscribed...

[@n057828]

Is it possible to have multiple caps charged and micro controlled by computer to run a motor hence to eliminate the use of a battery? And decharge caps but also charge them with solar

[@highwaysouth9015]

Wll it work bro ?

[@rborroto]

I'm trying to troubleshoot my Pentair 230v pool pump motor. It simply stopped running this morning after 7 years of running 7 hours per day. I replaced the run capacitor (30 MFD) and the motor still does NOTHING. No hum or anything. I checked the voltage at the motor to eliminate a faulty supply and it's fine, voltage checks out. The shaft spins easily by hand so it is not zeized. Should I test the motor and run it like you did, bypassing the capacitor? The cap I bought new is not returnable, they will not accept any returns, so I may have thrown away $15 bucks.

[@danielbaker9847]

I thought once it got its initial 'bump' from the capacitor and was up and running, it would be okay. That proves my theory wrong.

[@grayfurnaceman]

Daniel Baker That would be true if it were a start capacitor. The run cap is a little different. In addition to starting, it increases efficiency. GFM

[@danielbaker9847]

grayfurnaceman Thanks for catching my mistake. I am just beginning to learn. If you had not corrected me on this matter, I would have had problems later on from my misinterpretation.

[@wyatttipton9957]

In that case if it has just a normal start capacitor, could you spin the motor with your hand and give it power then will it start?

[@averyalexander2303]

Just out of curiosity, will running the motor with no capacitor damage it?

[@grayfurnaceman]

Yes, it will overheat or just not start. GFM

[@averyalexander2303]

Thank you!

[@JohnDoe-uq3mx]

almost like some 2 phase motor there it seems.

[@dutcher517]

John Doe two phase, lol.

[@fredsapplianceacademy]

appliance.academy