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Brian HVAC Guy
Brian HVAC Guy, HVAC Technician
Category: HVAC
Satisfied Customers: 921
Experience:  I have been an HVAC/R mechanic/technician for 30+ years.
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It all started last summer. The evaporator blower stopped

Customer Question

It all started last summer. The evaporator blower stopped working in my furnace in the basement. I observed the blower motor and it would rock back and forth and sometimes start slowly but then stop after a few seconds. I found another motor with the same
serial number and it worked but it seemed to be blowing so hard that it was blowing condensation all over the inside of the cabinet and leaking out onto the floor. I've been putting towels down daily to soak up the water. I then found en ECM controller for
the original motor and replaced it but it gave me the same symptoms as the original motor. I put that ECM controller on the replacement motor and it still blows condensation all over the inside of the cabinet. It is a RUUD AC system and the motor serial number
is 5SME39HL 0489. When I originally had the problem I looked at the ECM controller and did not notice any burnt components. I did an Ohms check on the original motor and all 3 pins checked out with 10.7 Ohms. Both motors have the same serial number 5SME39HL
0489. I also had an issue in the winter with the outside heat pump tripping the breaker from time to time. I'm thinking that the 2 problems are related because of incorrect air flow (too strong). There's a $50 bonus in it if you can help me resolve this issue
unless it costs a ton of money which I don't have.
Submitted: 2 years ago.
Category: HVAC
Expert:  Brian HVAC Guy replied 2 years ago.
Hi I'm Brian and I'm here to help! If by "ECM controller, you mean the air handler control board where the motor wiring harness connects, by process of elimination, you've determined that both motor drives are fine and the original control board in your unit was the problem. It would appear that even though the serial numbers on both motors are the same, the drives on the motors are programmed for two different model units. I would swap the drive end off your old motor, put it on the new motor and use the new control board. That combination should give you the correct airflow. Conversely, if by ECM controller you mean the drive on the end of the motor, then you still haven't found the correctly programmed drive for your motor and you may have to go to a Ruud parts wholesaler to get the right drive to achieve the right airflow. The problem with the outdoor unit tripping the breaker will most likely not be related to the indoor airflow being too high. You're just not going to load up a compressor enough to trip the breaker by increasing the indoor airflow. I would be willing to bet the more likely issue with the breaker tripping is either a loose wiring connection(s) somewhere in the circuit, maybe even at the breaker, or a weak compressor run capacitor. Try those things and look for a loose wiring connection, change the compressor run capacitor and let me know how that goes. Thanks, -Brian
Customer: replied 2 years ago.
I do mean the drive on the end of the motor. I went to a website ( and put the serial number of the motor and they claimed they had the correct ECM controller for the motor serial number 5SME39HL 0489. I could send you the documentation that they provided but I got the same symptoms on the original motor (starts slowly then quits) and on the replacement motor (blows too strong). I could send the documentation they sent me and a document I found for Rheem/RUUD motors. Am I looking for a motor, with controller that mounts on that motor, that matches the serial number of the furnace?
Expert:  Brian HVAC Guy replied 2 years ago.
Comfort Gurus are a great group. Yeah just for kicks and giggles go ahead and attach the docs. You can attach them with the paper clip icon in the text formatting toolbar or the Attach Files button. One or the other of those buttons are in the reply dialog box you type responses to me in. Yeah, when I order a new ECM motor for a unit, I go to the MFGs wholesale rep and give them unit model and serial. I've never gotten a wrongly programmed drive that way. I must admit, I've never tried to order a replacement ECM motor with only motor data. -Brian
Customer: replied 2 years ago.
Here are the documents I've collected
Expert:  Brian HVAC Guy replied 2 years ago.
I've got all those too. They're just the standard generic ECM docs. Do you have a Rheem part number for the motor? ex. 51-nnnnn-xx-Brian
Customer: replied 2 years ago.
It's 51-24374-10 . This is actually the number I gave comfortgurus to get the ECM controller
Expert:  Brian HVAC Guy replied 2 years ago.
That's the correct motor part number. Does the module they sent have a Rheem part number on it? Same number format.
Customer: replied 2 years ago.
got to go out. I'll message you later
Expert:  Brian HVAC Guy replied 2 years ago.
Very good. I'm usually on from noon to midnight -ish EDT. I'll look for your next post. Thanks, -Brian
Customer: replied 2 years ago.
the part number on the controller is 51-104904-10
Expert:  Brian HVAC Guy replied 2 years ago.
Great, thanks! I'll do some research on that while you're out.
Expert:  Brian HVAC Guy replied 2 years ago.
Ok I've done a ton of reading about your unit, the original ECM2.3 motor that was in it and the Eon drive that Comfort Gurus sold you. It all appears to be kosher and correct. The ECM2.3 has gotten replaced with the Eon and supposedly the Eon modules are backward compatible with the ECM2.3 motors as long as you use the adapter bracket. I personally can't attest to this. I adopted a practice years ago with the advent of the first ECM motors not to replace motor modules but instead order and replace the entire motor/module. This after going through the initial growing pains of migrating to ECM motors to begin with. I found it was a much safer practice for customer satisfaction even if it wasn't under warranty and even though it's a more expensive route for them. One call and done! I'm not sure if there's an issue with the Eon module working with your Ruud interface board or what is going on with your installation since the module you got (51-104904-10) crosses as the correct Eon replacement for the 51-24374-10 ECM2.3 motor. Did you call tech at Gurus? They should be able to tell you what's going on. On a side note, you could try adjusting the bank of dip switches on the interface board (unit control board) for a lower system airflow. That may solve the problem even though it seems like an interim fix. Switch 1 ON will lower the base cfm of the unit from 1200 to 1000 and switches 2 and 3, OFF and ON respectively will lower the base setting switch 1 selects by -10%. Switches 5 and 6, Off and Off respectively will reduce the base cfm setting by -15% as well but regardless of any switch setting 2-6, the maximum reduction from the base cfm setting of switch 1 will be -15% total. Clear as mud right? Let me know how I can help further,Thanks, -Brian
Customer: replied 2 years ago.
I just pulled the blower assembly out again thinking that the RUUD/Rheem serial number might be different than the original motor but it is the same. I also took a photo of the dip switches. Any idea of how I could set these dip switches to get the proper air flow? I'm attaching the photo. Thanks.
Expert:  Brian HVAC Guy replied 2 years ago.
Sure, I referred to them in my last post but since you sent a pic, let me review your switch settings. Also is appear you have a humidistat attached to the system? Is that correct? Also, It would appear you might benefit from the installation manual. It should have been left with your system. Click Here for a copy of the manual. The dip switches are covered in there and I can translate the techie stuff if there's something you don't understand. Thanks,Brian
Expert:  Brian HVAC Guy replied 2 years ago.
If you turn SW-1 and SW-3 ON and all the rest OFF, you get the lowest possible airflow under all thermostat/humidistat settings that your unit can supply. This will be 1000 CFM -15% or 850 CFM. That may be too low for your system but you said the current motor/drive you have is supplying way too much airflow so it may work just fine! -Brian
Customer: replied 2 years ago.
No luck, I put switches 1 and 3 to on and everything else off and didn't notice any change in motor speed. The motor started right up and seemed to run at full speed. Not sure if it's the motor or something else at this point. Maybe the control board is not sending the proper signal to the motor to control the speed. I'm not sure how to determine that. I'm going to try cleaning the evaporator. Maybe it's not draining properly
Customer: replied 2 years ago.
Hi Brian,
Are there any voltage checks that I can make to see if the motor is getting the right signals to control speed?
Expert:  Brian HVAC Guy replied 2 years ago.
Good morning!The 16 pin plug/cable on that board with the dip switches (blower control board) sends signals to the motor depending on what mode the thermostat's in, what plus or minus signals are being sent, dip switch CFM settings and so forth. It sounds like at this point you've got either a failed fan control board or the interface cable between them. The motor is getting the signal to run but not the rest of the data to run at the desired CFM. I've not diagnosed that board for signals, just for ok/failure. I'm sure there are signal voltage checks that can be done. The diagnostic tool we use in the trade makes it unnecessary to do such checks. There are different models such as the Techmate or Zebra tools that do the checking for us. They make it simple/stupid :) They are fairly expensive so usually not worth it for the end user to buy. I can look and see if I can find more info but the board and cable are pretty cheap so it may be easier just to replace them. Click Here for an online source for the board. I'll have to look for the cable. Thanks, -Brian
Expert:  Brian HVAC Guy replied 2 years ago.
Click Here for an online source for the 15/16 pin ECM interface cable.-Brian
Customer: replied 2 years ago.
The jury is still out on whether or not you actually provided help for my issue. So far I have done anything different or tried any other troubleshooting outside of what I already did short of changing dip switch positions, which didn't help. I'm waiting until I get the control board and wiring harness before I make any further comments or evaluations.
Expert:  Brian HVAC Guy replied 2 years ago.
Very good then, keep me informed. Thanks, -Brian

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