AC motor airco - Page 1
Forum section: electronics / repair

author: Kjelt
author_rank: Super Contributor
timestamp: January 27, 2015, 04:08:43 pm
content: Hi all,i am more a digital microelectronics software type than a 230VAC mains AC motor type so I need some help.I have a small airco that cools a room to 12 degrees C , 24/7 52 weeks a year and after 8 years or so it now and than the fan starts to make loud whining noises. Sometimes it does this for hours so loud it gets us at night out of our sleepThan it is quiet again for sometimes days in a row.So I called the firm who installed it and they can't really help me: the motor is "maintenance free" so they can not service or lube it. It can also not be replaced by them since they and the manufacturer no longer have it in stock.So their only way out is to replace the entire system, which costs a lot of moneyThe questions:- what is the most plausible cause for the noises , it is AFAICS not ab obstruction in airflow, could it be the bearings, or ?- is it possible to lube or clean the ac motor or bearings in any way it no longer makes these high pitched noises or is it maintenance free as claimed so replacing it with a new one the only solution?- anyone know where to get replacement motors like this one or do I first need to unbox the whole thing for a manufacturer name, type ?thanks already for the help

author: SeanB
author_rank: Super Contributor
timestamp: January 27, 2015, 08:17:27 pm
content: Manufacturrer and model of aircon for a start, as the motor could be one of 2 types. First would be a plain AC induction motor with capacitor, using either speed control via a triac or with speeds via taps on the motor. Other type is a DC brushless motor, most likely a 24VDC unit. Either one is rather generic, with the AC motor being very cheap, and the most common fault being a capacitor that is low in value. DC motor is more expensive, and the control method varies but most are DC voltage control with a feedback of rotation.Most common cause though of a noise from the fan is the bearing opposite the motor, which is generally a sleeve bearing or a roller bearing running in a rubber housing. You take the filter off, undo the typically 3 screws holding the front cover on ( and often the screws holding the electric access cover, of course after the power is disconnected at the mains) and remove the front cover. Then you undo more screws and remove the condensate tray, and undo it from the tube ( typically it has a metal wire lock held with a screw) then clean the dirt from it. With that off then you remove the controller housing and boards so you can undo the motor screws and release the motor from the unit Then remove the fan unit and the bearing will be loose at the far end.Clean the blower and remove the motor and lightly lubricate the connector, and put some light grease on the bearing inside, then put the kit back together. Then it will likely be silent for years again.A quick temporary fix though is to take some spray oil, and use the long tube to get a little between the fan end and the bearing at the non motor end. That should stop the noise and prove it is the bearing.

author: Kjelt
author_rank: Super Contributor
timestamp: January 27, 2015, 09:27:47 pm
content: Ok thanks a lotthat will be a nice task for one of the coming weekends.It has no brand or model, this is the inside unit and it was custom build by the dutch firm that delivered the airco, the outside unit was also custom made but has a standard airco unit from Italy.It is actually a special kind of cooler for a winecellar that cools to 12oC and 80% moisture (where normal airco inside units would freeze up).Hopefully I can get the outside off since they used a lot of rivets, it was a custom job. Thanks at least I now know there is an opportunity to fix it I will investigate further and get back when I get inside.

author: Kjelt
author_rank: Super Contributor
timestamp: March 14, 2015, 11:06:49 am
content: I have been ill for over 3 weeks so haven't been able to start this but today I have started.I first dismounted all the surrounding plasterwork and was able to see now that it was not a custom job as they told me (or remember 12 years ago)but that the evaporator is a standard Searle TG2-7.I opened up the metal cover that keeps on hanging on its hinges since all the airco tubing goes through it in the back (can not remove totally),but I had enough room to disconnect and remove the motor with fanbladesI removed the fanblades and was able to see that it is a one phase 240VAC motor,the manufacturer and type of the motor:A.O. SmithSer 4NA UC16085F Model type AB2N6259K240VAC 0,46A. see picture.Unfortunately as you can see the top (and back) plates are fixed with rivets not with screws. So I have as a question, whats next?How can I lubricate the bearings just put some oil or WD40 in it ? Or can I only replace it with a new oneAnother question: how can I make this motor run a bit more silent during the night, can I use a Variac to put 180VAC-200VAC on it during the night and switch with a relaisto 230VAC if the cooling starts? Or is it damaging for the motor to run on a lower voltage? Or any other circuits to do this?Thanks all

author: Kjelt
author_rank: Super Contributor
timestamp: March 14, 2015, 11:16:04 am
content: I see that the motor can be ordered new so that is hopefull but I rather lubricate this one and have it running again this weekendhttp://www.e-team-shop.de/oxid.php/sid/x/shp/oxbaseshop/cl/details/cnid/ea645be7f1e75e155.06737963/anid/4d351ee8dec73fc18.60897226/pgNr/3/Luefter-Motor-Fasco-Mod%3A-AB2N6259K-240V-50_60Hz-0.46A-211-015-104-Class-B/http://ascateringsupplies.co.uk/part.aspx?pCode=ASC34250

author: SeanB
author_rank: Super Contributor
timestamp: March 14, 2015, 11:30:40 am
content: Those covers look like they are pressed on, so likely you can pop only the one off and have the motor apart to get to the bearings. You likely had a pair of long bolts that went through the entire motor, through those 2 square holes in the top and a corresponding pair at the bottom, so simply clamp the motor lightly in a vice ( lightly means it can still move) resting those lugs on the top of the vice, and use a drift to tap off one pressed steel end cap. Then you will have the bearings, and can pop off the steel cap if present or pull off the 2 6000 series metric bearings and get 2 new ones. Typically you want a 2RS version which has rubber seals on the ends so lasts longer, or just pop off the outer steel cover and repack with either NGLI1 grease or use some gearbox oil ( manual box not auto box, must be a SAE 90 or so, or a viscosity range from 450 to 630 heavy oil) then put back together, making sure to put all the spacers and shims back in the right order they came out, and place the cover on the same orientation it came off.Done quite a few of these, and after a few they do work well afterwards. Even can be done to those horrid fans with sleeve bearings, though there a hammer to adjust clearances is needed.

author: Seekonk
author_rank: Super Contributor
timestamp: March 14, 2015, 11:38:51 am
content: WD40 is not oil. It often "lubricates" by dissolving hardened grease near the location. A thin oil would be best as it needs to wick into the scintered bearing, I often use automatic transmission fluid. This often washes out debris and allows the shaft to bounce around creating new noises. I have done this lots of times and the condition often comes back in 6 months to a year as the lube dissipates because it was never pulled up into the bearings. That motor will tap apart. Use a screwdriver/chisel with hammer to tap on the sheet metal edge and keep rotating. If the fan shaft is scored it can be polished but will likely vibrate due to increased clearances. This fan motor is fairly generic in size. Use what time you get to find a similar replacement that will mount with some adaptation.

author: Kjelt
author_rank: Super Contributor
timestamp: March 14, 2015, 11:44:01 am
content: SeanB thanks a lot for the assist, I do see a lot of english words I have no clue what they mean so please could you enter "beginners" mode for me an assist with it line for line so I don't end up with a broken motor.QuoteWith covers you mean the entire two black metal surroundings not only the small innerplate with 4 rivets, right?Quotecorrect I already took them out before the picture, this was where the motor was mounted with.QuoteI have a large wooden vice in the garage, so I have to clamp the vice around "lugs", what are the ''lugs" are these the 4 sticking out parts of the middle of the motor (the metallayers also used in transformers?)Quoteoops what is a drift some sort of flat metal like a screwdriver and i tap it at the side of the metal surroundings to remove it? Which one should you advise then the one where the axis sticks out and the fan is mounted (call that top one) or the other bottom one?I stop for now to see if I got it right, sorry might be a bit frustrating for you as an expert but I never done this and english is not my first language and with technical terms I absolutely do not trust google translate (has cost me dearly in the past)Thanks

author: Kjelt
author_rank: Super Contributor
timestamp: March 14, 2015, 11:46:21 am
content: Quote from: Seekonk on March 14, 2015, 11:38:51 amThe problem here is also that the motor is mounted inverse so the axis where the fan is mounted is pointed to the ground which does not help putting oil on top since the gravity will just make it go the wrong way, but that is just a simple thought I have. But I can run it for 24hours standing up ofcourse before placing it back.

author: Seekonk
author_rank: Super Contributor
timestamp: March 14, 2015, 11:58:51 am
content: I edited up my last post before I saw new replies. It doesn't take a lot of oil, more doesn't make it better. Inside some motors have a felt wick that stores oil and the back bearing generally has no access unless motor is taken apart. A drift is a long round pin with a flat edge, chisel or screwdriver will do. Rivets hold bearing assembly only. Bolts hold the motor together long term, it easily comes apart. Run the motor for 24 hours then clean up and install.

author: Kjelt
author_rank: Super Contributor
timestamp: March 14, 2015, 12:21:16 pm
content: Ok I understand (I think) and did the vice and slowly tapping the cover and it just fall offNow I am going into the city to see if I can find some oil that matches SeanB's description. Thanks all, to be continued.

author: Kjelt
author_rank: Super Contributor
timestamp: March 14, 2015, 12:28:41 pm
content: Ah the whole axis comes out now beautyRunning the bearings with my fingers see picture the left one turns 10 times before stopping so that one is pretty ok, the right one does not even turn half a round so that one is the culprit.Just curious is it possible to replace that bearing. It seems like it is pretty stuck to the axis, do you need special tools to remove it? Or would you all suggest re-oilng and see if it can be made to spin again?Thanks all. Very interesting.

author: SeanB
author_rank: Super Contributor
timestamp: March 14, 2015, 01:05:16 pm
content: The bearing is a press fit on the shaft, and they also have a steel sleeve over them to fit the housing ( looks like it originally used a different bearing so the steel spacers are fitted) so you place a large screwdriver either side between the bearing and the motor rotor, place on the wood vice so the screwdrivers are holding it then tap on the top of the shaft with a hammer ( preferably use a small socket that fits the shaft, likely a 11mm cheap chinese one you do not like, so it does not burr the end of the shaft) and the bearing will come off. Then the new one is put on till it is the same depth using a metal sleeve ( pipe piece) so you only hit on the inner race of the bearing so you do not damage it.

author: Kjelt
author_rank: Super Contributor
timestamp: March 14, 2015, 01:29:13 pm
content: Ok thanks if I order a replacement I will try that.For now I have found ball bearing grease (they use it for bikes ball bearings) and I wonder how to get the grease inside the bearing between the balls?It looks like it is almost completely sealed?

author: Ian.M
author_rank: Super Contributor
timestamp: March 14, 2015, 01:39:11 pm
content: *NEVER* pry (lever) between the armature core and the bearing.You may want to try flushing the bearing with thinners, with the armature shaft down and the windings protected by foil to keep the thinners out of them, spinning the bearing vigorously to see if it frees off and if it does, then get it up to 100 deg C or so with a hair drier or temperature controlled hot air gun to drive out any remaining thinners (do it outside - fire risk!) then dunk the bearing while hot, still on the shaft into oil (types as suggested earlier) so it sucks some oil in as it cools as a short to medium term cure while you get the right bearings.N.B. If you apply too much axial pressure on the outer race, or hit one race while the other is fixed, it will trash any ball bearing by brinelling the bearing surfaces of the races. This means that removal by supporting it on two screwdrivers and driving the shaft out should only be done if the bearing is totally FUBAR or a new bearing is available. A puller that acts solely on the inner race wont brinell the bearing but an ordinary hook type puller that holds the outer race will.

author: PA0PBZ
author_rank: Super Contributor
timestamp: March 14, 2015, 01:45:54 pm
content: Quote from: SeanB on March 14, 2015, 01:05:16 pmIt looks like there is some rubber between the bearings and the steel sleeve? Anyway, the bearings are very common NSK 608Z, you can buy them anywhere. They are used in skateboards, 3D printers, whatnot.

author: Kjelt
author_rank: Super Contributor
timestamp: March 14, 2015, 01:52:17 pm
content: In the mean time I used a little bit of IPA on the bearings and they now run like new.Now i probably have to regrease them, the ball bearing grease is to thick to get inside so I will go in to some carshop to find the manual gearbox oil to soak them in for awhile.

author: BradC
author_rank: Super Contributor
timestamp: March 14, 2015, 02:05:37 pm
content: Just use clean motor oil, that will buy you some time (weeks/months). While it is working find a motor rewinding shop or auto electrician and then at a convenient time take the armature in and have them replace the bearings. They have the correct bearing pullers and presses and will have access to good quality bearings at the right price. Should not cost more than a few tens of dollars and maybe a sixpack of beer. Then it'll outlast the remainder of the A/C unit.I did the bearings in an exhaust fan recently. They are about 30 years old. I soaked them in shellite (like a light lighter fluid) to get the old oil out and then soaked them in 10W30 synthetic motor oil. They are still a little noisy, but they run fine. I have replacements sitting on the shelf for when they finally fail or I get around to replacing them.My policy now is whenever doing _any_ work on anything that contains a motor, I replace the bearings. Cheap insurance. Don't buy bearings on E-bay *ever*.

author: SeanB
author_rank: Super Contributor
timestamp: March 14, 2015, 02:29:04 pm
content: That is why I love Bearing Man. They do decent bearings, seals and if they cannot supply a seal they will simply make it for you.The bearing can be regreased by simply prising the cover off on the side that is away from the armature, so it has another cover in use. Careful as the bearing cage is right under that, so if you go too deep you break it or damage it ( same thing, it binds on the balls). then pack grease in and assemble without the cover, as the housing will do the same function for a long time.You can buy bearings that are 2RS ( 2 sides rubber seal ) or 2S ( 2 sides steel dust cover) as well as 1RS ( one side only rubber), 1S ( one side steel dust cover) or even 0S for use in an oil bath and external seals. A lot of motors use a 1S or 1RS, as the other side will have a shaft seal in any case, and then they can put in a grease nipple for the bearings so you can put oil in the bearings during service. I replace gearbox bearings that have a 2S bearing with the 1S when it runs in oil, so the bearing gets better lubrication.

author: BradC
author_rank: Super Contributor
timestamp: March 14, 2015, 02:34:58 pm
content: Quote from: SeanB on March 14, 2015, 02:29:04 pmYes, but.... once the bearing is noisy then re-greasing is just prolonging the inevitable. The surfaces are already damaged, so it's not a matter of if it will fail but when. Bearings are cheap (relatively). Clean and grease(or oil) them to get you through the night, but replace at the next convenient opportunity.

author: SeanB
author_rank: Super Contributor
timestamp: March 14, 2015, 02:39:16 pm
content: I have some machinery that uses a C3 tolerance high load bearing. New price for each is $1000 plus. Repacked with Molyslip grease a few years ago and it is still working, though I suppose at some point I will have to order a new set of bearings or the complete motor. Not any more noisy than new still, and a lot quieter as well.

author: albert22
author_rank: Regular Contributor
timestamp: March 14, 2015, 04:18:16 pm
content: This may help you:A gear puller is needed. Try to borrow one or improvise a similar action. A last resort would be to split the bearing with a chisel by first denting it with a dremel. Be careful to not damage the shaft.http://www.stu-offroad.com/axle/d44/d44-2.htmWhen using the chisel do not hold the shaft just rest the bearing in a solid base like an anvil.When installing the new bearing, note that the force is applied to the inner race. In this way no damage is done to the bearing.

author: Seekonk
author_rank: Super Contributor
timestamp: March 14, 2015, 05:07:18 pm
content: That shaft end bearing is easy to press on at the factory. Removing it is not so easy if you haven't had experience and some specialty tools. It is easy to do a lot of damage. Think long and hard before preceding. Pulling a dust cover and regreasing can buy a lot of time. If serious about new bearings, put it back together and spin down the shaft diameter to remove any imperfections and make it slightly smaller. No need to force the bearing the entire length.

author: BradC
author_rank: Super Contributor
timestamp: March 15, 2015, 01:23:39 am
content: Quote from: SeanB on March 14, 2015, 02:39:16 pmYes, but had they come to a screaming, vibrating halt before you re-packed them?

author: SeanB
author_rank: Super Contributor
timestamp: March 15, 2015, 04:50:14 am
content: No, just noisy more than the new sound, so I was looking to replace, then got the price so decided to repack with moly grease. They shut up immediately, either just from having more grease or from the moly additive. Other gearboxes also got the additive, which did make them run a lot cooler and quieter. It did tend to foam the oil though, which was good to actually lubricate the top end bearings a lot better than splash lube. Still had to eventually pull it to replace main bearings, they got to the point where they killed the main seals and I had to pull it to get them changed as I do not have a puller that big. Fun lowering that 80kg motor off the box then unmounting the 150kg box off the shaft. I drilled into the concrete ceiling and installed a 2 ton hook eye and rawlbolt using epoxy for added strength. Chain block is great.

author: Kjelt
author_rank: Super Contributor
timestamp: March 15, 2015, 12:09:18 pm
content: So just finished mounting everything back again and it is running nicelySo thanks to every contributor so far for making this happen, much obliged to you allNow two questions left:1) I was looking for replacement bearings:http://www.klium.nl/zoeken?orderby=position&orderway=desc&search_query=kogellager+608&submit_search=Zoeken&p=2and it resulted in a staggering amount of 608 bearings, can anyone point me to a translation table that explains the differences between all these types, they vary from €3 to €40 a pieceSean you mentioned the RS2 types but which of the 9 possible ones should I choose for my application?Quote2) How can I reduce the rpm on this one phase motor so it makes less noise at night? I tried the variac to 170VAC but it makes no difference so that one is out. It it possible at all with this motor?Thanks all for all the help so far, it is very much appreciated

author: cs.dk
author_rank: Unknown
timestamp: March 15, 2015, 12:21:29 pm
content: Quote from: Kjelt on March 15, 2015, 12:09:18 pmYou can see the standard bearing designations here: (This is the prefix-table, remember the suffix-table also)http://www.skf.com/au/products/bearings-units-housings/ball-bearings/principles/bearing-basics/basic-bearing-designation-system/prefixes-and-suffixes/prefixes/index.htmlIe. a C3 type bearing has more clearance than a normal bearing.I think a 1-phase in - 1-phase out VFD is the best way to reduce the rpm's. They are rare though.

author: Kjelt
author_rank: Super Contributor
timestamp: March 15, 2015, 12:53:57 pm
content: Quote from: cs.dk on March 15, 2015, 12:21:29 pmThanks that makes things more clear, still not sure what to choose besides the RS2 that Sean advised but I will call the company and ask their recommendation replacement.QuoteI just googled a bit on that term and I read that you also have to have a special motor that has better insulated windings to withstand the induction peaks. Hmmmm I do not think this cheap motor will have that.So another option would be to go to 24VDC? Those I can just PWM or does that also require a special circuit. It does not have to be stepless or something like that I just need two settings, one normal full power and one a bit more silent during the night.I am not sure how I would calculate a replacement motor, can I just take the same power so, 240VAC 0,46A is aprox. 110W so if I get a 24VDC 100W motor with the same axe diameter would this work or do I need to calculate more parameters like rpm and torque or something like that?

author: Seekonk
author_rank: Super Contributor
timestamp: March 15, 2015, 01:00:52 pm
content: Motor can be slowed down SLIGHTLY by increasing motor slip with reduced voltage. My furnace has used a buck transformer for ten years to reduce speed, maximum reduction in voltage is about 20%. Downside is motor heating increases as airflow decreases.

author: BradC
author_rank: Super Contributor
timestamp: March 15, 2015, 01:32:38 pm
content: Quote from: cs.dk on March 15, 2015, 12:21:29 pmUse a 1-phase in - 3-phase out VFD (they are everywhere and cheap) and just connect the motor between two of the phases.

author: Seekonk
author_rank: Super Contributor
timestamp: March 15, 2015, 01:57:18 pm
content: Many 3 phase inverters will work on a single phase. Many 3 phase inverters will fault driving only two phases.

author: cs.dk
author_rank: Unknown
timestamp: March 15, 2015, 02:06:09 pm
content: Quote from: BradC on March 15, 2015, 01:32:38 pmCoolI have that setup on some cealing-fans, but i wasn't sure it was safe, so I said nothing bout it.I just checked the voltage and frequence, and hooked the thing up. FWIW Omron/Yaskawa V1000 can run in this configuration, without problems.

author: BradC
author_rank: Super Contributor
timestamp: March 15, 2015, 02:17:05 pm
content: Quote from: Seekonk on March 15, 2015, 01:57:18 pmI've never found one that can't have the phase balance fault disabled.

author: SeanB
author_rank: Super Contributor
timestamp: March 15, 2015, 02:20:22 pm
content: With this application you just use the cheapest bearing with either 2RS ( rubber seals) or 2Z ( steel dust seals) and you will be fine. As to slowing it down it is a matter of getting a motor with more poles, so basically you are stuck with the speeds it comes with, unless you just use a SCR and cut every second cycle out so it runs slow. It will make noise at 25Hz though. You do get some motor speed controls that use pulse skipping to reduce the frequency of the motor.

author: Kjelt
author_rank: Super Contributor
timestamp: March 18, 2015, 12:23:20 pm
content: Even with the re-greased bearings this unit makes too much noise so I now definitely want to replace the whole motor and fan with a more silent version.I found this one from Papst (see datasheet below) it is ofcourse a different mounting so I have to measure if it fits.The thing that I have absolutely no idea about is the chart on the last page.The original unit has a 23cm fan with a 490m3/hour air flow.The Papst fan can even on 1000rpm do this but this depends on the Pfsthe increase in pressure. But I have no idea how to measure that.So what do you guys think just try it and see how it works out?Other suggestions with the same mounting as the original but more silent?

author: BradC
author_rank: Super Contributor
timestamp: March 19, 2015, 02:55:55 am
content: Quote from: Kjelt on March 18, 2015, 12:23:20 pmYes, but you've already ruined the bearings leading up to the re-grease, so they'll be functioning but probably quite noisy. I'd spend the couple of bucks and get *new* bearings before tossing the whole fan unless it was this noisy when you first put it in and you just put up with it.Once a bearing becomes noisy, you will *never* get it back to like-new noise levels with a re-lube. Noise is caused by damage and it's irreparable.Replacing a fan on paper without having all the pressure and airflow measurements becomes an expensive case of trial and error. Don't let me stop you however.

author: Kjelt
author_rank: Super Contributor
timestamp: March 28, 2015, 03:07:15 pm
content: Quote from: Kjelt on March 18, 2015, 12:23:20 pmCan anyone answer these two questions please:- if you have three fans of 150m3/hour air flow mounted next to eachother will this result in about 450m3/hour air flow ?- if one fan produces 31dB of noise how much dB will three fans produce?Thanks, i am looking at using three 12V industrial fans:http://www.noctua.at/main.php?show=productview&products_id=83&lng=de&set=1

author: cs.dk
author_rank: Unknown
timestamp: March 28, 2015, 09:54:08 pm
content: 40,5 dB if I calculated correctly. + maybe some unknown added turbolence because of the design change.I still don't get it. Bearings costs next to nothing, renew them, and it will run for 10 more years. You still have the opportunity to slow it down a little.

author: Kjelt
author_rank: Super Contributor
timestamp: March 28, 2015, 11:45:21 pm
content: Quote from: cs.dk on March 28, 2015, 09:54:08 pmThanks for the calculation, it will be much better than the 230 fan.The reason is that even with brand new bearings (which I don't have the correct tools for to change them) this motor still makes too much noise, we moved the bedroom next to the wineroom where this thing is working and I must say now I turn it off every night I sleep much better than I ever haveTurning it off every night is not an option in the summer, and the suggested products needed to slow it down costs much more than three brand new silent 12V fans that produce the same airflow and are easy replacable and maintanable by me.

author: BradC
author_rank: Super Contributor
timestamp: March 29, 2015, 12:48:23 am
content: Those muffin fans have wildly varying airflow figures depending on pressure on either side. The only person who can answer your questions is you, and the only way you can do it is to just do it. So why don't you do what you plan to do and then come back and tell us if it worked?My guess? Too much static pressure at the fan exit will choke the airflow and you'll ice the evaporator completely stopping all airflow.Muffin fans are mostly configured in puller applications precisely because they don't deal will static pressure well at all. We've tried to tell you, so prove us wrong.

author: Kjelt
author_rank: Super Contributor
timestamp: March 29, 2015, 02:03:13 pm
content: Quote from: BradC on March 29, 2015, 12:48:23 amBecause I hoped there were some people on this forum that know this stuff and did this before and can tell me right from wrong in this situation.The only advise I got is to replace the bearings or the same noisy motor which is understandable and good solid advice but I am now looking for an noise improvement so I need another motor or fan. If there is someone who can show me a 230VAC or 12VDC or 24VDC equivalent power and axis motor that makes less noise I would be very happy, I am not able to find it.QuoteThanks for the advise this is good stuffSo if I understand you correctly it would be better to place these fans on the outside of the coolingevaporator so that they suck the air through it instead of blowing it through it, is that what you mean with pulling application?QuoteWhen did you try to tell me? This is the first time I consider the low voltage fans since the first Papst 230VAC fan is too large for the hole and there is no room inside and I am not willing to spent more then a day metalworking a hole and innerworks to make it fit and then find out it doesn't work. If my experimentation fails I will have to be able to reverse it all.If nothing works than I have no alternative than to revert to a new original motor or new bearings and a shop that can replace them.

author: Kjelt
author_rank: Super Contributor
timestamp: May 15, 2015, 12:58:28 pm
content: Update:In the meant time I ordered replacement bearings and I bought the three Noctua IP67 fans and they have a lot of airflow. In order for them to suck the air through the evaporator unit and not sideways I had to make a construction to make it airtight against the box on the outside. Up till now not a big success.So today I replaced the bearings of the motor which was quite a challenge since the pulleytool would not fit under the bearingThe low bearing was a no go, the upper bearing I sanded off the pulleytool hooks more flat so they would just fit.After that it was a piece of cake to remove the first bearing.The second took me a while with some self made pulleytools which failed but in the end I used two large screwdrivers and wricked it up. It came off eventually.I mounted the low bearing by using a drillpress which worked great and I made a small alu pipe, mount it in the drillpress and pressed to the upper bearing which also worked quite nicely.Mounted the motor back and.................... a lot less noiseMaybe not low enough to sleep again (since we are used complete silence by now) but still a very good improvement.Thanks all for the recommendations and support esp SeanB many thanks, it is much appreciated