Need help with my Rudd gas furnace (electrical)

Discussion in 'HVAC' started by jeffmattero76, Jan 16, 2018.

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  1. Jan 16, 2018 #1

    jeffmattero76

    jeffmattero76

    jeffmattero76

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    Ruud Model # UGED-06EMAES

    Serial # BU50703 M47922089

    *

    I had the top cover off for a day or two making sure that the furnace was working properly before putting it back together. I had some time today, so I wanted to do a leak check, even though I had not removed or changed any of the gas lines. I also tightened the screws where the 18 gauge wire connects to the board. There is a single green light on the board that simply shows that the board is receiving power. It does not blink error codes.

    *

    I am not sure if it gives you any clues, but, while tightening the screws to the IFC, my screwdriver rubbed against the sheet metal box that surrounds the board, and I saw a spark.

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    In any case, the t-stat had been set back to 60 degrees at this time of the day. In order to test for leaks, I set the t-stat to “HOLD 75” and went back to the basement to check for leaks. I waited and waited, but the furnace never even attempted to come on. I went up and checked to make sure the t-stat was set correctly, and it was. I reset the breaker, I turned off the kill switch for 10 seconds and then turned it back on, and nothing. I have two limit switches on this furnace, and both show continuity. I checked the leads going to the inducer, and I show no voltage. At the board, I show 125 volts between hot and neutral (at the connectors on one edge of the board where a humidifier would connect). I followed the incoming leads to the transformer, and they also show 125 volts. The output of the transformer shows 27 volts.

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    In measuring the wiring contacts, I have the following with the t-stat calling for heat:

    ·******** R-C ***-* 27 volts

    ·******** R-W **-* 0 volts

    ·******** C-W** - 27 volts

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    There are also G and Y contacts, but they show no voltage regardless of which other contact I touch. As I understand it, the G only gets energized when the board calls for the blower, and I believe the Y is for air conditioning.

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    I have seen a video that mentioned a fuse on the board, but I do not see one. Before removing the board from its metal box, I wanted to know if it is possible that there is a fuse mounted on the back of the IFC.

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    Thanks for any light you may be able to shed on this for me.
     
  2. Jan 16, 2018 #2

    maxdad118

    maxdad118

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    Pictures would help, most newer boards usually have a small 3A fuse. Have you tried jumping it at the board? Transformer shows good if you get 27v. Is there a limit you may be missing?
     
  3. Jan 17, 2018 #3

    jeffmattero76

    jeffmattero76

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    I have a house full of people right now, so I will post a picture tomorrow. At the board, I tried jumping R to C, W to C, and then R to W. I got nothing. To m as key sure I understand jumping, I used a piece of 14 gauge wire with both ends stripped and touched the screws as described. Is that correct? If the fuse would be on the front of the board, I don't have one on this system. Is there a possibility it is on the back side of the board?

    Thanks for responding.
     
  4. Jan 17, 2018 #4

    jeffmattero76

    jeffmattero76

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    I have a house full of people right now, so I will post a picture tomorrow. At the board, I tried jumping R to C, W to C, and then R to W. I got nothing. To m as key sure I understand jumping, I used a piece of 14 gauge wire with both ends stripped and touched the screws as described. Is that correct? If the fuse would be on the front of the board, I don't have one on this system. Is there a possibility it is on the back side of the board?

    Thanks for responding.
     
  5. Jan 17, 2018 #5

    maxdad118

    maxdad118

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    No, it should be visible on the board. Also make sure you are depressing the door switch(if it has one?). Jump across R and W. You may have fried something on the board if that doesn’t work....
     
  6. Jan 17, 2018 #6

    jeffmattero76

    jeffmattero76

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    With the door switch depressed (taped down) I read 125 volts on L1/neutral on the board.

    With the t-stat calling for heat I get the following readings:
    R/C 27VOLTS
    R/W 0 VOLTS
    C/W 27 VOLTS

    With the t'stat not calling for heat, I get the following readings:
    R/C. 27 VOLTS
    R/W 27 VOLTS
    C/W. 0 VOLTS

    If I can figure out how to post the pictures here, I will do it shortly.
     
  7. Jan 18, 2018 #7

    jeffmattero76

    jeffmattero76

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    Can someone direct me on how to upload pictures to this thread. I cannot figure it out.

    In doing more testing and looking, I am getting 125 volts to the board and to the transformer. I am getting 27 volts from the transformer to the board, but, for some reason, there is no voltage being sent to the inducer motor. There is no fuse on the board (which I have removed ), and I see no burnt spots on the tracings. I have checked the tracings for continuity from each of the screws to the end of each tracing, and all show continuity. Thetefore, I am in the process of finding and ordering a new board.

    Just for educational purposes, is there a way to check each of the many components on the board? I think most of them are small diodes, but there are a couple of resistors, and other "block" shaped pieces, but I have no idea what they are called.
     
  8. Jan 18, 2018 #8

    nealtw

    nealtw

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    If you are on a computer I can help.
    Load the picture on the computer.
    When you are posting just below is a button, Manage attachment.
    That bring up a page hit button choose file
    Find your picture and double click it.
    And hit Upload
     
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  9. Jan 18, 2018 #9

    bud16415

    bud16415

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    Click on the paperclip in the menu. Then click on choose file and then find a photo on your computer and double click it. Then hit upload and the photo will be transferred to your post and will show up on your post as an attachment.

    That’s how to do it from a computer doing it from a phone is a little different.

    As to checking components on a printed circuit it is pretty hard to do as the traces interconnect everything. Most of the time what fries is one of the chips and unless the board has a chip socket so it can be removed and replaced you have to toss the whole board.
     
  10. Jan 18, 2018 #10

    nealtw

    nealtw

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    Are you on a computer?
    Manage attachments below
    Choose file picture
    upload
     
  11. Jan 18, 2018 #11

    nealtw

    nealtw

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    Interesting I posted twice here but my post does not show up, that explains two. But Bud's like showed up so I know he is getting them.

    It must be time travel. I am just 4 minutes ahead of myself.
     
    Last edited: Jan 18, 2018
  12. Jan 18, 2018 #12

    bud16415

    bud16415

    bud16415

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    I liked your post before you wrote it.
     
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  13. Jan 18, 2018 #13

    nealtw

    nealtw

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    There's a time for that.
     
  14. Jan 18, 2018 #14

    jeffmattero76

    jeffmattero76

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    Neal - no, I am on my phone. Do you know how to add pictures when doing it from a phone? Thanks!
     
  15. Jan 18, 2018 #15

    jeffmattero76

    jeffmattero76

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    Ok, thanks. As I responded to Neal, I use Tapatalk only on my phone.
     
  16. Jan 18, 2018 #16

    nealtw

    nealtw

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    No help here sorry.:hide:
     
  17. Jan 18, 2018 #17

    jeffmattero76

    jeffmattero76

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    No problem. Thanks.
     
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  18. Jan 22, 2018 #18

    maxdad118

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    Did you get this issue figured out? Do you have heat again?
     
  19. Jan 22, 2018 #19

    jeffmattero76

    jeffmattero76

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    Yes, we have heat and the furnace is working as it should. The issue was that the trap was blocked. Once I sucked the water out with my shop vac, and cleaned it out, it works perfectly. Thanks.
     
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