Is a GE 5-wire blower motor speed-controlled?

Discussion in 'HVAC Heating & Cooling' started by leejosepho, Feb 11, 2007.

  1. leejosepho

    leejosepho DIY scratch-pad engineer

    Please bear with a short story here to explain my posting of this question, as I do not want anyone thinking I am out trying to put any HVAC people out of work ...

    I had gone to the store to get some stuff for my bathroom project, and in the parking lot I happened to see an elderly woman I am inclined to help, and after she told me her furnace blower had quit working, I spent the rest of the day getting it going once again. She had called a regular furnance company, but when they saw her gas (Goodman) furnace sitting in her living room with no ductwork and an exposed exhaust going out through the wall about eye-high, they had many good reasons for turning away even though our temperatures around here have been single-digit for a couple of weeks now.

    This was the dirtiest motor and blower I have ever seen, but I was able to get the assembly out without choking too badly -- four dead mice and a large nest went into the trash bin -- and everything actually cleaned up rather nicely. The only slippery substance immediately available was some cooking oil, and I used that to re-lubricate the wicked bearings after I had cleaned them up as best I could.

    Sitting on the floor in front of the furnace, the blower assembly would not come up to speed unless I blocked its output about 50%, and after it was back in the furnace and the cabinet was closed up, I could still speed it up quite a bit by restricting one of the two registers in the plentum.

    This capacitor-start motor has five wires: 2 black, 2 red, one yellow.
    This motor is wired through what appears to be a small (Essex) controller that is about 3 inches long and 1-1/2 x 1-1/2.

    My question is this: Does this woman have a weak motor, bad bearings dragging it down or a bad controller not bringing it up to speed?

    She will definitely need a new motor before next winter, but I am hoping to help her get through another few weeks with this one.

    I did a search but could not find this motor: GE 5KCP39HGM614S
    Last edited: Feb 11, 2007
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    First, this is a joke, right? A gas furnace in the living room, no duct, horizontal vent, dead mice in the blower, vegetable oil lube?

    There are so many red flags here, the best thing you could do is call the fire department and have them condemn this thing. There are so many issues regarding carbon monoxide, fire ( how is the gas piped to this thing?) you could get this lady killed.


    As far as your specific question, the GE 5KCP39-series motors are all proprietary parts for the manufacturer, in this case goodman. Is there a capacitor on the motor? No way of telling if this is a multispeed or variable speed motor. If the furnace is old, it may not be either.
  3. leejosepho

    leejosepho DIY scratch-pad engineer

    No, this is a very sad situation, but it is no joke. This woman's since-deceased father first installed a furnace in the corner of their living room many years ago, then somebody later replaced it with this Goodman. There is a bracket tied to the wall to keep the furnace from tipping over, the gas line comes in with 1/2" black, there is a plentum (with two register openings) that goes most of the way to the ceiling, the vent rises at least a little above horizontal, the dead mice and nest are now gone and the cooking oil was very sparingly added to the wicked bearings. I had thought about coming back to my own house to get some wheel-bearing grease, but I thought that might be too thick.

    What lube should actually be in those bearings? And, do you know whether new bearings can be purchased?

    Yes, there is a capacitor mounted on the blower housing, and with two wires running back to the motor in addition to the five wires I have already mentioned going to the Essex whatever-it-is.
  4. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Is there a problem with the motor? If you have the model # of the goodman furnace, I can probable see a wiring diagram. I gather it is older than the GSD/GMS models, but let post the model # if you can.

    Motors like this typically use 20 weight oil. The motor tag should indicate that. These motors are theoretically repairable, but the cost would be many times the cost of a new motor.
  5. leejosepho

    leejosepho DIY scratch-pad engineer

    I am not completely sure, and that is why I wondered whether it might be speed-controlled somehow.

    When I first arrived, the motor could not turn itself at all because of all the dust compacted within and around it. Honestly, I have never before seen a motor as dirty as this one was. After I had cleaned it, yet prior to adding any lube, it would turn up to speed (1075) without the direct-drive blower wheel attached, but I would guess about half-speed after being completely installed back in the furnace. At that point, I again removed the blower assembly and added the oil to the motor bearings ... and now the motor runs up to speed as it should (as best I can guess) but it will still run faster if restricted just a bit.

    I have sent queries to two companies to see whether I can get a new motor for this furnace, and I hope to be able to do that very soon. However, I do not presently know the model number of the furnace, itself.
  6. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    If this woman is a s destitute as it seems maybe there is an organization that can help her out with a small new furnace installed right.
  7. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    There should be a model # plate, possibly inside the upper cover. With that number, I can give you the goodman part# for the motor. Places like Grainger can probably cross reference the motor you have.

    A furnace like this might typically have a multi-speed motor ( not a variable speed or speed controlled motor). It could be as many as five speeds, although you do not have that many wires. One speed is selected for the heating mode and possibly another speed is selected for the air conditioning mode. This way, you can balance the speed to the size of ductwork, and allow for different BTU heat as opposed to the tons of cooling. Many places have an extreme need on one side ( e.g. Phoenix in the summer) and a modest need for the other (mild Phoenix winter)
  8. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    There should be a model # plate, possibly inside the upper cover. With that number, I can give you the goodman part# for the motor. Places like Grainger can probably cross reference the motor you have.

    A furnace like this might typically have a multi-speed motor ( not a variable speed or speed controlled motor). It could be as many as five speeds, although you do not have that many wires. One speed is selected for the heating mode and possibly another speed is selected for the air conditioning mode. This way, you can balance the speed to the size of ductwork, and allow for different BTU heat as opposed to the tons of cooling. Many places have an extreme need on one side ( e.g. Phoenix in the summer) and a modest need for the other (mild Phoenix winter)
  9. leejosepho

    leejosepho DIY scratch-pad engineer

    So then, I assume this motor's fluctuation of rpm when restricted even just a little is a result of something being out of order.

    I have received a phone number for one possibility of a source for a new motor, and I will check that out tomorrow. If that does not work, I will check with Grainger, but I believe this motor has its three brackets permanently attached. If I cannot find a motor in the next day or two, I will go look for a Goodman tag such as you have described.

    Thank you!

    PS to Cass: Are we not that "organization"?!
  10. leejosepho

    leejosepho DIY scratch-pad engineer

    Well, that worked for two weeks, but now the bearings have developed a bit of a squeal and the motor's thermal protection overload switch has shut it down. It still turns fairly easily, though, so now (possibly tomorrow) we will see just how bad the bearings really are and whether a complete disassembly, cleaning and the proper oil will keep the motor running for just another few weeks!
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