Surplus electronic parts : https://epartsconnect.com
Stock and Crypto AI Prediction : https://stocksignalslive.com

Eric Mele demonstrates how to replace a 3HP motor and install a control box with a motor starter. He also rewires the system and puts the low-voltage wires in a sealed junction box.
Before Eric went to work on the motor, it had burned out, was replaced, and burned out again. He also notices insect nests in the panel, the contactor in the supply airstream, a missing keyway, and an oversized breaker, which are all less than ideal.
The pulley also cannot spin and is in poor shape overall. Eric attempts to remove the pulley with a two-jaw puller, but the task proves difficult; the motor shaft doesn't spin at all. Since the pulley has suffered so much damage, Eric replaces it entirely.
Eric disassembles the contactor, which has been warped from the motor burnout. That contactor tripped the 60-amp breaker.
Eric wires the motor for the 208-230v application. The high-voltage wires go to the motor starter and feed into the top, and the wires go down into a new 20-amp breaker. All of the wires are #12 wires. Additionally, the motor starter has a high-voltage coil, and a relay pulls in the starter. If the overload relay were to change state, it would stop the motor. The wiring is configured so that the compressor will not run if the contactor is not pulled in; this is a common practice in commercial equipment .
The high-voltage wiring joins with the low-voltage wiring in the junction box. Eric ties in the condenser to the thermostat (white), float switch (breaking red), 600v rated wire to starter enclosure (green or yellow), and common (blue) wires. He labels everything to keep track of all of the controls.
When Eric runs the blower, he checks the amperage at the control box. He discovers that the white wire gives the cooling signal to the condenser, so he decides to switch it with the yellow wire at the box. He also draws a schematic, fixes any bent components, and seals up the conduit and all the holes he finds to prevent moisture from getting into any of the electrical components.
Before walking away from the job, Eric also adjusts his relay and tests it to see if it stops the unit when it's supposed to.
Read all the tech tips, take the quizzes, and find our handy calculators at https://www.hvacrschool.com/.
Learn more about the 2022 HVACR Training Symposium at https://hvacrschool.com/symposium/.


This is eric with calo services and hvac school and today we're getting into this mess. What have we got here? We've got ta polish, this turd this motor burned out and was replaced and everything seemed okay to who was out here and it burned out again. So we're going to investigate why now, as you can see with this equipment, there's a lot of less than ideal stuff going on here that we're going to correct having a contactor in the direct supply airstream - probably not a good idea. So what we have here is a.

I believe this is a magic air, ducted outdoor cabinet air handler that is piped over to that condensing unit over there. It's about a 10 ton, if i remember correctly - and we are going to get started going through this - we're going to replace the motor we're going to put a control box here with a motor starter downsize. This breaker, which was a 60 which was tripped amazingly so that must have been quite the burnout and tighten up any other installation or shouldn't, say installation, just any other issues we can with this unit. Within reason, i mean it's still a turd but it'll be a polished turd, so i checked into the wiring and it was correct but, as you can see here, the keyway isn't in there.

That's a problem. This thing spun and i'm gon na try to move the phone, slow, we're right up against the motor, and i can't spin this now. It could be that it's just so damaged internally that it won't spin, but i can't get it to budge. So i know this pulley is not in great shape, we'll address that later, if needed.

But let me see if i can get it loose and get it off of this motor shaft see what the heck's going on, but all that wiring, i'm sorry. I moved the phone so fast and people complain about it in comments and i get it, but i'm not a cameraman sorry. So the contactors gone, the motor is unmounted. The breaker is gone.

All that wiring is gone and we're gon na rewire. All of that we're gon na put the low voltage in a sealed junction box in the bottom here and plug the ends so that it's not getting all wrecked by the supply air. This is one of the pullers i use for this type of job. Sometimes a three jaw will work better, which probably would in this application too, but the biggest one i have is what i need to use, and i only have a two draw for that.

This thing's fighting me the whole way off it still won't. I mean now the pulley's spinning on the shaft, but it still wouldn't spin. I can't spin that motor shaft at all, so it's about off of there gon na look into the electric next. Once i get this apart start laying that out.

Oh look at that spider. That's a yummy spider, huh black widow, nice literally, everything was living in this panel. We had wasp nests, we had mud daubers and we got a black widow. Spider cool.

Is that the male? I don't know, i'm not a entomologist or whatever. That is probably saying the total wrong word, so this is the contactor disassembled seen worse, but doesn't look too great, but also you know this motor did melt while that was engaged so that didn't help anything and it tripped a 60 amp breaker on a motor. That's rated for, like nine amps, plus the service factor, so here's the point we're at the motor is roughly set and it's wired for the 208 to 30 volt, which means four five and six are wire netted to each other. Seven and one go to black eight and two go to red and nine and two or nine and three go to blue.


So that's all joined up there for the motor high voltage wise and that's going into the bottom of the motor starter. I have the loops. So you can easily grab amperage at the bottom there it's fed from the top of the motor starter, which is going down to our new 20 amp breaker. All the wire is sized for that.

It's all number 12 wire, the motor starter, has a high voltage coil. So this relay is to pull in the motor starter, so we have neutral run to one side of the motor starter coil, and then we have hot run to the relay the cooling relay, which runs through the overload relay on the motor starter and then back up And into a1 on the contactor to pull it in. So if this overload relay changes state the motor stops, what we also have is on the contactor normally open is we have yellow for the compressor? So if this contactor is not pulled in, the compressor will not run, and that is joined up with our low voltage here that we're gon na have in this junction box, with a whip going back up there and i'm gon na seal. This hole with silicone and put the wires back together.

Now, as far as i know, this is single stage, but interestingly white was hooked up from the condenser to the thermostat see one of these wires comes from the condenser where the transformer is located and one of these wires goes to the thermostat. So we have our float, switch tied in breaking red, that's how it was before, and we have our green going to our 600 volt rated wire into our motor starter enclosure same deal with our yellows and our blue, which is common, everything's labeled there, and i have It labeled that that's low voltage coming in and that's about it for the controls, the motor needs to be slid into position and the belt and pull well. The pulley needs to go back on and then the belt and we're just about ready for start up. Now.

The spider that's in there, unfortunately, is gon na be sealed in there, because i'm not going to be trying to smash a spider in a electrical panel and clean it out. I don't want to mess around with touching that spider. So what i'm going to do is i'm going to seal the openings with silicone from the inside put the panel cover back on, and that's going to be that we'll seal up this top here, we'll seal up going into the unit that will be dealt with. That's pretty much it besides testing operation, of course, which will come once we get it started and making sure our amperage is good once this thing's running.


So i'm going to work on all that next and we'll take a look at that when it's done all right. So i checked rotation on this. I had to end up getting a replacement, pulley and belt that other pulley wouldn't go back on. It was pretty trashed from spinning on the shaft, so i got a new pulley.

I got a slightly different size, one because the other belt was not the other pulley. The whole thing wasn't being used. So i measured where the belt landed in the old pulley and got one based on that and we'll get it adjusted where it needs to be based on amperage and estimated unit airflow, which we will use measure quick to find. So i already bumped this and made sure it's spinning the right way.

One thing i got to do, though this blower is: i need to check amperage, so the full load amps is 9.4 at 230 and 9.7 at 208. So, let's measure our incoming voltage to see if it's 208 or 230., it is in fact 205. So we will set this accordingly. This dial here i'm gon na change.

Right now, we're set for seven amps, i'm gon na set it for nine amps. I think that should be fine, so we have the blower running right now i had to put a different pulley on it, because the one i had would not go back on. I guess it got damaged on the old shaft and it just would not go so we're drawing 7.8 8.4 and 8.4, so we're pretty high on our blower amps at 208 we can do 9.7, so i have the motor starter set for nine right now now i Was looking at the wiring and the white wire is actually what's giving our cooling signal back at the condenser over here? This thing is uh not much better than the other unit, but i'm gon na have to make a slight wiring swap, as you can see, white is tied in to our cooling coming back into all this mess here, and this is a single stage unit. So i'm gon na have to switch it in the junction box inside the unit and and use the yellow is not being used.

So i will just break white, which is cool on this unit, which is compressor, i should say, and it is a straight cool. It's 88 degrees in the store. I'm gon na get some readings on this unit. Make sure it's running right.

The blower seems to be going about as fast as it can be. That's our control box, which we were showing before i siliconed all the openings in there, except for a couple small openings down low in case water gets in there. I want it to come back out, although it'll come out the front anyway, but all the holes. I sealed up just kind of the concentric rings: have those little gaps if you're familiar with those and those are not sealed.

I sealed the conduit coming out the top. I know it's not ideal to come out the top there, but i really didn't have room to do much else. I could have came out the side with liquid type, but i decided against it. That's pretty much it i'm gon na bend this cover.

It's a little bent up gon na get my hand seamers and bend it back. I'll probably draw a schematic in here for the control panel switch that yellow make sure that everything works correctly, but it's 88 degrees in the store. So i'm gon na let it run for a few minutes and clean up some stuff and just kind of let it do its thing for a while, so that i can get some real readings off of it. Since this motor starter has a range that goes lower than our motors, drawing, let's give it a test.


Shall we try not to get struck by lightning here because of course, the thunderstorm just rolled in so we're tripped? I don't hear my condenser running, so that's good. That means that sorry for the quick phone movements i'm doing this one-handed. So if you look at my contactor my aux terminal, that's disabling my condenser. Let me reset this guy up to nine and a half there.

We go it's rated for 9.7 with this motor, so we're going to go to 9.5. So that's the resolution i can see and that's what we need we're at 8.6. So we should be fine there and that's about it. For this call.

I just got to button this thing up and i'm good to go and for those who want to see not my best schematic i've ever done, but it's something right. So it's not that complicated of an arrangement here just a relay to pull in a motor starter. So hopefully, people understand what's going on and on a commercial unit like this, it's not uncommon to use a relay to pull in a motor starter like this or big contactors, because going through a regular thermostat and trying to pull in one here and one in the Condensing unit plus, all the other controls can overload the little relays on the thermostat, so this will be much easier for it to cycle on and off than just directly cycling a contactor thanks for watching our video. If you enjoyed it and got something out of it, if you wouldn't mind hitting the thumbs up button to like the video subscribe to the channel and click, the notifications bell to be notified when new videos come out, hvac school is far more than a youtube channel.

You can find out more by going to hvacrschool.com, which is our website and hub for all of our content, including tech tips, videos, podcasts and so much more. You can also subscribe to the podcast on any podcast app of your choosing. You can also join our facebook group if you want to weigh in on the conversation yourself thanks again for watching you.

15 thoughts on “3hp blower motor replacement”
  1. Avataaar/Circle Created with python_avatars OrganPianoGuitar says:

    Lectra contact cleaner or Lectra Electrical degreaser to kill the black widow. Last thing you need is to have that thing multiply and the potential to get bitten. Back before I was in the trade, i was in law enforcement and one of our sergeants got bit in his patrol car, and was in ICU for two weeks, lucky to have made it.

  2. Avataaar/Circle Created with python_avatars Michael Goodman says:

    Who the hell did that old electrical!? You should be ashamed of yourself! Are you in Ottawa ?

  3. Avataaar/Circle Created with python_avatars RJ_Make says:

    Whoa, that is one sexy looking distributor head.. ;~}

  4. Avataaar/Circle Created with python_avatars Josh Pearson says:

    Why do you think they did a split system and not a rtu

  5. Avataaar/Circle Created with python_avatars EpieVlog says:

    nice work and clean. great job

  6. Avataaar/Circle Created with python_avatars Hola! NICKLE& DIMEz says:

    Can you show more on how you wired the controls?

  7. Avataaar/Circle Created with python_avatars Hola! NICKLE& DIMEz says:

    Nice work! Good that you did loops for amp draws.

  8. Avataaar/Circle Created with python_avatars Gostevo79 says:

    So just so I’m understanding and I’m pretty green. You did away with the contactor which was 24v coil controlled and you added a motor starter with a amp overload but I’m guessing either all you had was a line voltage coil or they don’t make one with a 24v coil because you needed the low voltage control.

  9. Avataaar/Circle Created with python_avatars Eassyheat/ Cooling says:

    Wrong pulley, and that box is whether proof put it on the top of the unit and Come in the back.
    Nice way to make the schematic for the next person!👍🏻
    🥃🥃🍺🍺🍺🍿
    Stay safe.
    Retired (werk'n)keyboard super tech. Wear your safety glasses!

  10. Avataaar/Circle Created with python_avatars Brian Mcdermott says:

    Very instructional . Thanks Eric. Service area Nepean??

  11. Avataaar/Circle Created with python_avatars Jim Spier says:

    No mention of motor service factor??

  12. Avataaar/Circle Created with python_avatars Howard Blasingame says:

    Nice work Eric. Keeping old units running is difficult & requires thinking outside the box.

  13. Avataaar/Circle Created with python_avatars Diabloshell says:

    Great work but having to silicon everything like that is kind of trash, I'd recommend emt with raintight fittings personally.

  14. Avataaar/Circle Created with python_avatars Roger F says:

    Good clean work.

  15. Avataaar/Circle Created with python_avatars Waylon Wells says:

    First 👍

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.