Replacement AC fan motor very weak.

Well gents. I got the new new motor installed today. The battlestation is now fully operational. Lesson learned: Be as careful and have as much attention to detail with parts as you are with the actual work and don't blindly trust the "pros" at an RV service center. Thanks again for all the help.

Thanks for the update. Sorry you had this problem.

The parts shop that gave me the wrong motor ordered me the correct one and is going to exchange it with the one they gave me. With the shipping time and my schedule, I won't be able to install it until the week after the 4th of July. Once I get it in, I'll be sure to hop back on here and post an update so you guys can all have some closure. ;)

Well sir what is the rest of the story? Hope you have the right motor now and all is well.

I pulled the cover off to check the wiring and take another look at the motor. The sticker on top which lists the specs of the motor indicates the direction of rotation. The new motor is spinning the direction it's made to spin, but that is the wrong direction for my AC. The old motor label also has rotation direction (which is the way I need it to spin) on it but it's so faded I didn't know it was on there at all.

Long story short, the shop gave me the wrong part and I was too dumb to double check it. Hopefully they'll let me return the thing so it won't be a waste of $100 in addition to the waste of time.

Thanks again for all the help guys. I don't think I would have noticed it spinning the wrong way without all the advice.

PS. It's impossible to install the motor itself backwards because of the mounting brackets.

Lazarus Alessandria wrote:
The wires from the new and the old motors are identical.

With the current motor, low blows slower than high so I don't think they're swapped but they are both very slow. Also, "low" on the old motor was about twice as fast as "high" on the new one.

The motor had mounts welded onto it so it could only go in one way. Also the shafts were different lengths and wouldn't have put the fans in the right places if I somehow managed to still put it in backwards.

You'll have to forgive the dumb question... but the condenser fan should be pulling outside air through the fins into the AC housing right? or should it be pushing air from inside the AC housing through the fins and outside the AC housing?

OR

You put the fan motor in backwards! Take it out and turn it around - problem solved! The motor rotation is not normally reversible on these motors. Take a magic marker and draw an arrow on the motor housing. Take it out, turn it around and put it back in watching which way it's supposed to turn.

Ceiling fans run both direction via a switch. I would think swapping wires would make the motor run the opposite direction just like the fan.

Thanks for all the advice so far despite my sporadic updates. The cost is at the storage lot across town so I can only work a little bit at a time before work.

This morning I was able to see the direction of rotation and it looks like the squirrel cage is spinning the wrong way. It's possible that it's not running slowly and I just assumed it was because it's much quieter and barely putting out any air. In my mind that leaves two possibilities.
1. Dometic makes two motors that are identical except their rotation direction and I got the wrong part, which seems absurd. I think the new motor has the direction of rotation labeled so I'll double check that tomorrow, just in case.
Or 2. I almost definitely screwed up the wiring, even though it seemed so simple. I guess there's no such thing as idiot proof.

Someone mentioned that swapping leads to the run and start capacitors could make it spin backwards but as far as I can tell, there's only one capacitor up there. It's got three poles Herm, Fan and C. The motor had two wires to the cap. Brown to fan,and white to C (with all the other white wires). It's possible that in the heat and beating sun I swapped those, I guess but I thought I double checked. Would swapping the white C wire and the brown fan wire cause it to run reverse? At this point I don't care if the colors don't match up, I just want it to work. All the other wires (yellow, black, and red which I believe are the three fan speeds) routed to a 2 row by 3 column plug where they combine with a white, a blue and a yellow-green stripe, which plugs into a metal box which I assume is the control board. Is it even possible to wire the control board so that high and low both work in the same but wrong direction?

Chinese?

Lazarus Alessandria wrote:
Short version: I just replaced a failed AC fan motor. Now the fan actually works BUT it runs at around 20% of the previous speed and blows air very weekly. Also, when I set the fan to auto instead of low or hi, it doesn't blow at all. Help!

Background: I've got a Dometic 13.5K BTU ducted AC in my 2014 Coachmen Apex. A while ago the fan started having a very hard time turning on (click and hum but no turning even if I tried to spin it by hand) but after trying for a couple hours if get lucky and it would start. Once it started, it would run indefinitely. I replaced the capacitor and that didn't really help. Yesterday, I got it running after a struggle and it ran for a few hours until it started squealing louder and louder until the fan geadually slowed to a stop. I got a replacement for my model (457915.711CO) from an RV service place, same size, wire colors, wire lengths and connectors so I felt confident it was the right part. I installed it and now I've got the problem I mentioned above. Could it be a bad ground? Did I swap a wire? Anything? O was only 95% sure that I put the condenser fan back on the right way but that doesn't seem like it should me such a drastic difference in the speed the motor will turn. Any help is appreciated.

Could you post your before and after photos of the wiring, we might see something you missed.
If this is one of the newer Dometic I agree that the controller possibly bad as these use a 3 wire communicating tstat/control .