HVAC Blower Motor Rebuild slow? (1 Viewer)

[dbbowen]

Hi all I just took apart my blower motor, cleaned it, and replaced the brushes and now its slower than before. I tried some with short 1/4 inch l;ength brushes and 1/2 inch brushes as well and while the shorter brushes made the rpm faster than the longer ones, they still both were barely usable on high. Is there Something i missed in here? Maybe its binding in the bushings or something? Anyone else rebuild a blower motor and experience the same?

I cant find any NOS blower motors anywhere unfortunately, so was really hoping to go the rebuild route but it looks like i might have to go with a crappy four seasons motor

 

[BurntToast]

Hi all I just took apart my blower motor, cleaned it, and replaced the brushes and now its slower than before. I tried some with short 1/4 inch l;ength brushes and 1/2 inch brushes as well and while the shorter brushes made the rpm faster than the longer ones, they still both were barely usable on high. Is there Something i missed in here? Maybe its binding in the bushings or something? Anyone else rebuild a blower motor and experience the same?

I cant find any NOS blower motors anywhere unfortunately, so was really hoping to go the rebuild route but it looks like i might have to go with a crappy four seasons motor

do you have any photos or specs on the motor? I would be surprised there is only one replacement option in the sea of electric motors these days

 

[OSS]

just buy three 4 seasons motors

 

[Spike Strip]

@ToyotaMatt has OEM replacement on his website

 

[dbbowen]

do you have any photos or specs on the motor? I would be surprised there is only one replacement option in the sea of electric motors these days

I don’t have any specs or anything. It’s just the normal blower motor and the brushes were just normal carbon brushes it’s almost like there is too much resistance in the brushes or there isn’t enough voltage. Maybe the bushings are binding?

 

[Spook50]

Your commutator is way too worn and grooved, so there's very little contact between that and the brushes, limiting the current that can rotate the rotor assembly (main shaft). I had been investigating a refurbishment procedure but that would've required investing a couple grand (minimum) in a bench top lathe/mill combination among other investments, so likely would've have given me any realistic return.

Luckily, as @Spike Strip mentioned, there are Denso blowers available through @ToyotaMatt that work well with 12V 6x series Cruisers. Denso is Toyota's OEM as well, so you're not getting a cheap knockoff like the 4 Seasons garbage.

 

[Spike Strip]

FWIW, I have one of the 4-Seasons in mine and it's fine, blows well. They're made by Siemens, in Canada, and are (or were) sold under various brands. Though the Siemens motors are not as robust as the Denso OE, they work just fine. I have one of the ones Matt sells as a back up. Too bad his website is closed at the moment.

 

[Spook50]

FWIW, I have one of the 4-Seasons in mine and it's fine, blows well. They're made by Siemens, in Canada, and are (or were) sold under various brands. Though the Siemens motors are not as robust as the Denso OE, they work just fine. I have one of the ones Matt sells as a back up. Too bad his website is closed at the moment.

Granted this was several years ago, but I went through several 4 Seasons/VDO blowers that would only last a few months on average, and even when new didn't blow as well as a factory blower. Plus they were considerably louder with motor noise. I have pics comparing a Denso blower's rotor assembly to that of a 4S/VDO and the 4S/VDO is considerably smaller, with far less windings and a smaller commutator. Think I may have uploaded them a while back. I remember they were made in Canada and China (I had seen both stamps on the 4S/VDO blowers), but at least at that point, Siemens had nothing to do with them. It'd be nice if there's been a change for the better with them, because I had found specific Siemens blowers online that would fit the 6x series and been curious to get one and compare the innards to the 4S/VDO and Denso blowers.

 

[Spike Strip]

The one that's in my truck now, did have the siemens brand on the sticker, there was a close-out many years ago on ebay. It came in a 4-seasons box. It was quite an improvement over my shot stock one.

Current stock (within last few years from Rock Auto, I think):

12v is the same, diff part # (this one is for sale if anyone needs

 

[OSS]

I mentioned this maybe a year ago on a different thread... but the stock wiring for the blower motor is inadequate. It strangles the fan. I completely rewired the power wires to the blower using 10AWG duplex wire and holy crap the fan blew so much stronger. Like day & night difference.

 

[Spook50]

Oh yeah I forgot Unimotor was another brand I've seen on them, but none of the ones I ran had any Siemens branding, so I wonder if Siemens is now involved somehow. If they are, that could make for a serious improvement over the non Denso motors I had gotten in the past.

I'm tempted to try to try to get my hands on one and check out the guts.

Also @OSS is exactly correct. Ultimately I'd love to have much stronger wiring going to the blower motor that still utilizes the factory switch. That's yet another project that's a long ways down the road though, even if I get to it.

 

[OSS]

This is the power draw I measured from my fan:

LC blower fan power amps:
Speed:

1. 3.3A
2. 5A
3. 7A
4. 10A

 

[Spook50]

This is the power draw I measured from my fan:

LC blower fan power amps:
Speed:

1. 3.3A
2. 5A
3. 7A
4. 10A

That's just slightly less current per setting than the blower I'm using now pulls. I forget what brand it actually is, but it's NOT one of the parts store blowers and moves a healthy amount of air.

The blower motor resistor is a series of current resistors that works in conjunction with the blower switch to control how much current passes to ground after going through the blower. Going off of that principle, I have an idea (that I'm still trying to figure out if it's even feasible or not) of using that to control a PWM that would power a brushless motor using the factory switch. Essentially the PWM would set the blower at a certain speed based on the resistance to ground.

 

[CruiserTrash]

@OSS I’m assuming the hot wire comes from the switch and the ground wire joins a common ground bus somewhere?

 

[OSS]

The motor has two terminals. The plug on the original motor is polarized specific. It only connects one way.
I just check the polarity of the factory plug — which lead was positive and which was negative, then hooked up the fan the same way as the original.
I didn’t experiment with connecting the leads backwards because doing something like that can lead to undesirable consequences sometimes (possibly burning something out) so I don’t know what happens if the wires are connected backwards. It runs backwards?? Don’t know.

Also when I was camping a long time and sleeping in the car, I rigged a small 12V lightbulb inline with the fan power to create a BIG resistor. I think the bulb was one of my LC brake bulbs). The fan then only pulled about 1 amp and blew out a nice gentle breeze- enough to easily breathe with with all the windows rolled up during rain storms. Fan ran silent too at that super low speed.

Could run it all night sleeping on super low. Easy to recharge the battery the next day with the solar panel I had.

— Yeah when I rewired it, I just made sure the power went through the dash slider and resistor — and I put a suitable fuse inline.

 

[dbbowen]

Your commutator is way too worn and grooved, so there's very little contact between that and the brushes, limiting the current that can rotate the rotor assembly (main shaft). I had been investigating a refurbishment procedure but that would've required investing a couple grand (minimum) in a bench top lathe/mill combination among other investments, so likely would've have given me any realistic return.

Luckily, as @Spike Strip mentioned, there are Denso blowers available through @ToyotaMatt that work well with 12V 6x series Cruisers. Denso is Toyota's OEM as well, so you're not getting a cheap knockoff like the 4 Seasons garbage.

Dang, that’s too worn? It was JUST blowing normally. It would cut out and I had to smack it sometimes to work. All I did was clean it. I thought that groove was supposed to be there haha

I was looking for some denso units as Matt’s site is down and idk if anyone’s heard from him in a while. I couldn’t find any online anywhere

 

[dbbowen]

I mentioned this maybe a year ago on a different thread... but the stock wiring for the blower motor is inadequate. It strangles the fan. I completely rewired the power wires to the blower using 10AWG duplex wire and holy crap the fan blew so much stronger. Like day & night difference.

I like this idea. Do you have the thread where you described the wiring? Which wire did you replace? I might have to go with a four seasons unit as I can’t find any denso units anywhere online. Going to try some different brushes today and see if it changes anything but don’t have high hopes :/

 

[OSS]

where you described the wiring?

Like all my wiring projects, I just winged it off the top of my head, figuring it out as I went along. Not documented. I did it a long time ago so I don’t clearly remember the specific details.

 

[dbbowen]

Like all my wiring projects, I just winged it off the top of my head, figuring it out as I went along. Not documented. I did it a long time ago so I don’t clearly remember the specific details.

It do be like that sometimes haha

 

[Spook50]

Dang, that’s too worn? It was JUST blowing normally. It would cut out and I had to smack it sometimes to work. All I did was clean it. I thought that groove was supposed to be there haha

I was looking for some denso units as Matt’s site is down and idk if anyone’s heard from him in a while. I couldn’t find any online anywhere

That wear on the commutator is normal after many years of use. While the carbon brushes are softer than the copper, the copper will still wear over time. Your old brushes were basically "mated" to the profile of your commutator since they wore together, which is why many people report their fans running slower/weaker after replacing the brushes. If the commutator isn't excessively worn, it's just a matter of time to bed the brushes in to match the commutator's profile. To be honest I've never chucked one up in a lathe to turn the commutator all the way down to the phenolic and see just how thick that copper is. Looking at yours again though, it MAY be worth giving a chance to see if you can get the brushes to wear in. It's definitely very worn, but comparing to the couple scrap motors I have that I've gutted, it's not as extreme of a case as they are.