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  1. #1
    Join Date
    Dec 2004
    Posts
    2
    I have a roof top furnace that has a LH33WP003A ignition control board. I keep getting a random Fault code 8, "internal fault".
    The fault is cleared when the power is cycled. It may go days before it does it again, or once a day for awhile. Can't find any other problems. Any Ideas!!

    Terry Murphy

  2. #2
    Join Date
    Nov 2004
    Posts
    240
    Replace the board. There is no repairing the boards "internal errors".

  3. #3
    Join Date
    Nov 2001
    Location
    east kansas
    Posts
    8,030
    Make sure the flame sensor's wire is not touching to high voltage spark wire. Don't know if this will help, but remember something about a code not listed and the wires touching.

  4. #4
    Join Date
    May 2004
    Posts
    1,462
    Code 8 is an internal board check of the software. If you can reset the unit and it does not immediately come back but does it randomly as you describe, most likely you do not have a board problem so changing it would do you no good.

    As mentioned earlier, the most frequent cause is the orange ignitor wire and the yellow flame sensor wire being in to close contact with each other. If they are crossing, touching or just to close you could have this problem.

    Another thing to look at is the 3 wires (red, white and black) that go to the Hall Effect sensor on the back of the inducer motor. If one of these wires has rubbed and is shorting out to the cabinent you will get the same code.

    Last but not least, it could be dirty voltage or RF (radio frequency) interference. This could be from radio towers, satellite dishes, cellular telephones or misbehaving microwaves. This can be cured by installing a Data Line Shield (get them for $5 at Radio Shack), on the board. If you get to this point let me know and I can tell you where to put them.
    If all else fails....Try reading the directions!

    Tell it like it is and let the chips fall where they may.

    Any views or opinions stated here are strictly my own.


  5. #5
    Join Date
    Dec 2004
    Posts
    2
    I never thought about RF., a celluar telephone tower is on the same property, less than 500'away. Their is also alot of motor switching and a 50 hp. VFD in the facility. Where would suggest the filtering?

  6. #6
    Join Date
    Dec 2001
    Location
    Chicago, N/W burbs
    Posts
    8,004
    I may also be interested in this. We have 2 new Carrier RTU's (48GS?) and one has already locked out on internal fault with 9 flashes. There is a radio tower about a block away. Another non-electronic problem is that these are for two top-floor condos and no filter rack downstairs. Tell the yuppies that they're gonna have to get up to the roof and unscrew the access cover to replace the filters every month! Yeah, right I'm sure they'll be all over it!
    R2B4BTU

  7. #7
    Join Date
    May 2004
    Posts
    1,462
    The Radio Shack part# is 273-105. It is a lead shield in a plastic snap around enclosure. There are 3 places you can put it, I would recommend all three. In descending order of importance:
    1. On the yellow flame sensor wire as close to the board as possible. Make sure it has only single wire going through the shield. In other words do not put it around a bundled up part of the sensor wire.
    2. On the red wire from the transformer to the board. Again as close to the board as possible.
    3. On the L1 to the board/transfomer.

    Again, make sure the sensor and ignition wire are not close to each other or the shields will not help.
    If all else fails....Try reading the directions!

    Tell it like it is and let the chips fall where they may.

    Any views or opinions stated here are strictly my own.


  8. #8
    Join Date
    Jan 2006
    Posts
    1

    maybe this is a example ?

    I ran accross this thread from google. I was having the same problems as stated in the first line. No clear sign of RF source tho. I took the cover off and orange and yellow wires are right on top of each other. I am hoping this was the cause of the code 8 that i kept getting. I zip tied the orange wire back away from the flame wire. Guess we will see if this does the trick.

    What do you guys think?
    http://jason.iflight.org/hvac1.jpg
    http://jason.iflight.org/hvac2.jpg



    Jason

  9. #9
    Join Date
    Jan 2005
    Location
    Area 51
    Posts
    984
    Check the condition of the hall effect sensor wires to the board from the motor if they look like they have been hot look in the center of the board to see if you see a resistor that looks like it might have been hot. I have seen heat exchangers go bad and cause the wires to get hot and short out due to low draft pressure thru the heat exchanger. I have used iron core chokes to deal with RF noise before with good luck.
    "Paddle faster, I hear banjo music"

  10. #10
    Join Date
    Nov 2001
    Location
    east kansas
    Posts
    8,030
    What does a choke do? I've seen them on variable speed blowers.
    Beware of advice given by some guy on the Internet.

  11. #11
    Join Date
    Nov 2004
    Posts
    240
    You folks are mixing together two seperate fault codes. 9 flashes is the draft motor/hall affect sensor failure. Where sometimes if the flame sensor wire and the spark ignition wire are seperated as much as possible, it might go away. 8 flashes is an internal fault failure of the board. Replace the board. The two faults are not related.

  12. #12
    Join Date
    Jan 2006
    Posts
    1
    I have the same problem (8 flashes) on my LH33WP003A board (Carrier 48SS-036060321 package). Trying to find a replacement board with no luck. Local dealers and distributors don't sell the parts to owners. Called Carrier, but they suggested to contact dealers and distributors. On internet, I was only able to find LH33WP003, not LH33WP003A. Could anyone suggest where I can buy LH33WP003A? Or, can LH33WP003 be used instead of LH33WP003A? Do they have the same sets of connectors, so that it would be easy to figure out how to re-connect wires after replacement?
    Any reply will be greatly appreciated.

  13. #13
    Join Date
    Dec 2005
    Posts
    1
    call a tech

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