Have a master cool MMB10 and all of a sudden the fan runs slower on both speeds. Motor bad or something else?

Mine did that too. Either the motor needs to be cleaned out or the motor is shot. You can try to have the motor repaired. If that fails a replacement motor is about $120 if you can find one.

I posted this to another solution for someone looking for the motor:

Unless you can find an HVAC shop with a NOS motor for this unit you will not find a drop in replacement. Even if you do get lucky and find a NOS motor be prepared to pay nearly as much for it as you would a whole new evap cooler.

That said, there are motors out there that will work, but you're going to have to make them fit with custom mounts.

It's still a little spendy, especially if you want two speeds like the original motor had, but you can get out for $80 or less if you're willing to settle for one speed (on/off).

boatandrvaccessories.com has a "Packard 40066" compressor motor for $69 plus $13 shipping. It may work but has only one speed.

Basically what you're looking for is a "48 frame", 1/8 hp, direct drive, 110-120v, 1075rpm, 1/2" shaft diameter and around 3" in length (to give you flexability when mounting), "totally enclosed" or "open drip-proof" housing (NOT "open"). Rotation can be either CW or CCW as you can mount the motor on either side of the housing and some motors are reversable. If you've got the skill to custom make some mounts then you can probably fudge some of these specs. The ones you can't change are the 1/2" shaft and the RPM. Do not exceed 1075rpm. The blower assembly simply can't be made to go much faster in that housing and if you try you will overheat the motor and burn it out very quickly (trust me on this one!). Most of the cheap motors I've found are 208-230v and I just don't see the point in having a small 220v PORTABLE evap cooler, that's just dumb.

After a LOT of online research I've found the following motors that would be a suitable replacement, with all the above mentioned specifications. I'm sure there are more, but cross referencing this information for someone not in the business is tricky and time consuming.

AdobeAir 1/8 HP 115V Motor for Adobe MMB10A RF031095 $116.66
http://www.comfortgurus.com/product_info.php/cPath/25_142/products_id/7451

Emerson 4856 (k055srj4796722b) (www.emersonmotors.com)
A.O. Smith 136A (UH1036NB) (www.aosmithmotors.com)
Magnetek 136 (now owned by A.O. Smith - www.aosmithmotors.com)
Fasco D733 or D261 (fasco.com)
Marathon X924 (www.marathonelectric.com)
AdobeAir RK232A check acehardwaresuperstore.com
Emerson K55HXKZT-9867

Grainger.com is a good resource but they are expensive.


The motors listed are suitable replacements, but have only one speed, "ON" or "High".

Packard 40066 - 115v 1075rpm $69 - SINGLE SPEED

A.O. Smith 321P177
A.O. Smith 323P077
A.O. Smith 323P487
A.O. Smith 323P490
A.O. Smith 323P677
A.O. Smith U6521
A.O. Smith UH1016
A.O. Smith UH1026NB
A.O. Smith UH9034
A.O. Smith US1016
A.O. Smith US1016NB
A.O. Smith ORZ1026
Brownell MTG3206
Century C045A
Carrier HC37DX120
Emerson 9034
Fasco D834
Franklin 8736010170
Franklin 8715810230
Franklin 8735810180
GE 3081
GE 3206
GE 3950
Grainger 3M658
Grainger 3M800
Grainger 3M828
Grainger 3M829
Marathon X302
Mars 03950
Packard 70066
Packard 40066
R.E. Michael 1E521
Reznor 55682
Reznor 64678
Rotom R12177
Rotom R12834
Rotom UH9034
Trane MOT6195
Universal U136
Universal U177
Universal U380
Universal U566
Universal U730


Good reading for selecting a replacement motor:
http://www.aosmithmotors.com/WorkArea/DownloadAsset.aspx?id=13100

I suppose that if you found a smoking deal on eBay for an "Open" type motor you could try it, but I doubt it would last long and make damn sure that ****** is grounded well.

I found the replacement motor at comfortgurus as Emerson/Nidec 1129 for $109.65.The motor that came with MasterCool MMB10C was a Emerson K55HXKZT-9867. Emerson was bought out by US Motors, and then bought out by Nidec. After talking to a Nidec Representive I found that the Emerson Mod # is now a US Motors #1129. After a day of trying to find this motor, I finally got lucky with a persistent Grainger Rep that found it for me at Comfortgurus as Emerson/Nidec 1129.