What is the purpose of the plastic “condensate drain plugs” on the Fasco D728 furnace blower motor?

I needed a replacement for a GE motor 5KCP39PGP932AS 3/4HP for my American Standard Furance [Model No. AUD120C954H3]. On "Ask A Question", I found the reply from “HVAC1000” to “rtlalonde” that had a hyperlink to the eBay seller “electricmotorsite” who offered, as a substitute for the GE motor, a Fasco motor, Model D728. The Fasco motor was an almost identical replacement at an excellent price. Thank you “HVAC1000” and “electricmotorsite”.

One difference, though, is that the Fasco motor has 2 small yellow plastic plugs, one at each end of the motor chassis. Each plastic plug seals a tiny tube that goes from the outer surface of the motor chassis to the motor endplate, where the shaft sleeve bearing is located. It looks like a port for lubricating oil but there are no “OIL” markings near the plugs, or anywhere on the motor. The original GE motor did not have any similar plastic plugs.

I read the Fasco “Motor Installation and Safety Information” generic pamphlet that came with the motor to see if a certain type of oil was recommended for what I thought were “oil ports”. I found no information about lubrication or oil but the pamphlet had the following information under the heading of “Motor Mounting” that states:

“Condenser motors typically have condensate drain plugs on both endplates. Depending on the mounting position, the plug must be removed from the lowermost endplate.”


Given this information (above), can anyone answer following questions:
1. Are the small plastic plugs near each endplate the “condensate drain plugs” mentioned in the generic motor pamphlet? If so, why are the drain plugs provided if the plug for the lowermost endplate “must be removed”? Should both of these little plugs be removed and discarded, because they are necessary only for shipping the motor? [I removed both plugs from the motor.]

2. The motor is mounted horizontally in my furnace so that both endplates are at the same level. Should the motor be rotated so that the drain plugs, or ports they plug, are pointing down to allow drainage? [That is the way I currently have the motor oriented now.]

4. Is it true that the small yellow plastic plugs are not for motor “oil ports” and I should not put any lubrication down these little tubes?

3. Is this Fasco D728 motor called a “condenser motor” because it uses a 10 MFD 370 Vac external capacitor, and because capacitors are also sometimes call “condensers”? If not, why is it called a “condenser motor” and why does it need “condensate drains” if it is used as a blower motor in a furnace? What is the source of the condensation?

You asked a lot of questions and did it nicely too.

#1. You did the right thing. Removed and pointed down. Suppose this motor was used in a condenser outside and the shaft was pointed up?

#2 yep

#3 I believe so. No oil.

#4. The outside unit is also called a condenser. The inside coil and evaporator.

The motors are universal and therefore can be used in multiple applications. If you look at a dew point table, you can find the temperature in which water will condense given a surface temperature, the temperature and relative humidity of the air.
That's the source of the condensate.

The D728 motor is an indoor furnace blower motor. The yellow plugs are for oil if so equipped BUT according to the factory the sleeve bearings are lubed for life BUT the oil impregnated bronze bearings used in these motors can stand a small shot of Anderol 465 Synthetic oil every two years or so. See bottom of link page below.

http://www.fasco.com/pdf/Accessories_2008.pdf

The real condensate drain plugs are different and only installed on motors designed for outside use. There is one in the top and bottom of motors designed for outdoor use. You always ONLY remove one plug and that is the plug located at the motor end that is facing down. The other plug is always left installed or water will get into the motor when it rains since it is on the top. Some outdoor condenser fan motors also require a slinger which is a plastic dome shape device that fits onto the motor shaft before you install the fan blade.

Most if not all indoor motors are ventilated on the end bells. Most if not all outdoor motors are not ventilated on the end bells since that would allow rain to get into the motor. Outdoor condenser fan motors have a different rate of temp rise and a higher service rate than most indoor motors since the air movement can only cool the outer case unlike the indoor motors that allow air circulation into the motor since the end bells are vented.

Dew point can play a roll in outdoor rated motors and that is why they are equipped with a drain hole. BUT these drain holes are directly on top or bottom of the motor not on the side as the oil holes are located on the side if so equipped.


Dew point has nothing to do with standard indoor furnace blower motors since the furnace is enclosed in a home that has conditioned air and the motor is completely ventilated unless the furnace is used for special applications like car washes or other high moisture use areas.

There are many books about motors and how each group of motors differ depending upon applications and design specs. Many motors are misapplied and if that is the case those motors will have a very short life span. My main central air in this home is 32 years old and has the same condenser fan motor it was delivered with from the factory. My other two central air units in this home are 25 years old and they also have the same original motors. The reason they have lasted so long is that they are maintained as per the motor spec manual. They are lightly oiled every season and the run capacitors are checked. If the run capacitor is off over 5% in rate it is replaced as part of the service they receive.

I would also like to mention that all compressors are original with no measurable degrade in performance over the years. They are spec checked every year and capacitors and relays replaced as necessary. I also resistance check my contactor/starters and if the contacts show any resistance or flashing out of spec the contacts or the entire starter/contactor is replaced. If you take care of equipment it will last a long time but sad part is that there are not many service people that do this kind of severe service or know how to do it properly.
Good luck with your motor adventure.

Thanks, hvac1000. Everything you said in your reply to my questions makes sense.