I wasn't sure where to create this thread - Mods or Maintenance - but figured it best belonged here in Maintenance and Routine Care.
Hopefully a few members will find this useful...
I installed DC-DC voltage buck / boost , step up / step down converters for both of my 7500-K MaxxFans - will update this in one of the several MaxxFan voltage issue threads when I have time. We got 2 fans instead of A/C and 1 fan, mostly to KISS and avoid adding 100 lbs to the roof. So I installed the DC-DC converters and all was well. Ran everything through maybe 20 open/close cycles, different speeds, etc, and a couple of weeks later noticed that the rear fan would moan and groan when the lift motor was opening or closing the rain cover.
Front fan ok - could easily open/close it manually without powering it on, and the knob would keep spinning a little bit after being given a good spin.
Rear fan not ok - really hard to turn the knob, and no free-spin after spinning the knob; it used to behave just like the front fan.
Seemed weird since when installing the DC-DC converters I did the same thing on both fans: didn't do anything with the lift motor assemblies, didn't take them off, didn't unplug the motor wires, had killed the circuit ahead of time, just stuck the converters in series with the motor wiring, etc. Took the bad motor assembly apart and found 3 nice looking metal reduction pinion/spur gear sets, and no apparent problems. And could see no obvious mechanism used to cut the motor power when it reached the fully open or fully closed position. Was sort of expecting an arc of conductor material on a spur gear and spring loaded brushes that make or break the circuit based on gear position(s).
First bonus question: anybody know how it determines when to cut motor power when the rain cover reaches its limits of travel? Not simply a timer since it doesn't know (?) the initial position of the cover. Or maybe some sort of torque or current or whatever sensor that cuts power when the motor stalls out when fully open or closed? We certainly don't want the motor to remain powered when the cover is in the fully open / fully closed position and can't spin. Had no blown fuse issue.
Anyhow - on to the promised hot tip...
Figured I would go looking for a replacement motor / gear assembly. One seller on Amazon: $60 and out of stock. Any number of RV parts houses: $45 - $70 and all out of stock. Then found adventurervintl on Ebay - $35 and "More than 10 available". Same part number 10-20270 as on the original MaxxFan motor and gear assembly sticker, looked just like the original, but was referred to as a "Coleman Lift Motor 10-20270". Was willing to gamble 35 bucks and it showed up 5 days later. Spins nice and easily, and had an official AIRXCEL sticker on the plastic bag - likely a good sign. Guessing that Coleman sources their lift motors from AIREXEL Will get it installed next time the trailer is home from storage for it's monthly exercise. Also guessing that the same motor assembly would cost a lot more than $35 from our friends at AIREXEL.
https://www.ebay.com/itm/324958085596
Second Bonus Question: I am tempted to install the new motor assembly, use it a bit to make sure all is well, and then simply disconnect the +12 and GND wires that go from the controller board to the motor. I would be more than happy to manually open and close the covers by hand using the knobs (in particular since I often don't want the covers to auto-open all the way on power-on), and then simply turn the fan motors on and set the desired direction and speed using the usual buttons on the fan. Do any of you electronical gurus know if doing that would cause damage to the exceedingly expensive controller boards due to there not being any load on the lift motor output side?
If so inclined, get 'em while they're hot, available,and sort of cheap. I'm keeping my old one as a spare, JIC.
P.S. This adventurervintl Ebay seller seems to have a variety of RV bits and pieces for sale, including some Dometic stuff and some MaxxFan controller boards for seemingly good prices.
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