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  1. #1
    Join Date
    Mar 2010
    Location
    Arnold, Mo
    Posts
    447

    Blower Cuts Out In Cooling

    Carrier 48TFE012-A-611 ser 1004G50704
    This unit will run for about 1 minute normally and then the blower will cut out. The contactor for the blower motor has 27 volts at the coil until it cuts out. Then it shows no low voltage. The compressors and condenser fan motors will continue to run until the unit cuts out on low pressure. The blower will not come back on until you cut power to it from the disconnect and then reestablish power. It looks like to me, the only thing that could cause this condition is a bad board. I haven't seen this before and was hoping that one of you have. If you need all of the gauge readings and etc, I have them but I didn't post them since I don't think they are relevant to the problem. Thanks in advance!

  2. #2
    Join Date
    Jun 2008
    Location
    Rochester, NY
    Posts
    61
    Are you losing voltage at G when the blower cuts out?

    The only advice I could give without being there is just look at the wiring diagram and trace back what's providing 24 volts to the coil.

  3. #3
    Join Date
    Jun 2008
    Location
    Rochester, NY
    Posts
    61
    Nevermind that question...Forgot you need 24 volts to G on a carrier for the compressor to start.

  4. #4
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
    Posts
    2,304
    Quote Originally Posted by flanders View Post
    Carrier 48TFE012-A-611 ser 1004G50704
    This unit will run for about 1 minute normally and then the blower will cut out. The contactor for the blower motor has 27 volts at the coil until it cuts out. Then it shows no low voltage. The compressors and condenser fan motors will continue to run until the unit cuts out on low pressure. The blower will not come back on until you cut power to it from the disconnect and then reestablish power. It looks like to me, the only thing that could cause this condition is a bad board. I haven't seen this before and was hoping that one of you have. If you need all of the gauge readings and etc, I have them but I didn't post them since I don't think they are relevant to the problem. Thanks in advance!

    Does that unit have the fan contactor/ timer assembly. It just a fan relay with a small board
    attached to it.

    If it does or it gets it out put from a board jump the fsn coil wire to R to keep it running and then monitor the out put at the board.

    Not much to those Carrier RTUs.

  5. #5
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,724
    Go to the economiser board if it has the 4 LED`s on it and bypass the G terminal so the board doesn`t control the fan. Then look for corrosion on it. Change as neccessary.
    UA 100

    It takes three people to do anything around here. Two do the work, one explains to the crowd of people who showed up when they seen smoke and flames.

  6. #6
    Join Date
    Jan 2010
    Posts
    6,590
    Check the fan logic for power in and out also the blower relay. Check t-stat as well.

  7. #7
    Join Date
    Mar 2010
    Location
    Arnold, Mo
    Posts
    447
    Thanks for the replies. I'm going back today so I'll let you know if your suggestions worked.

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,581
    What did you find.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  9. #9
    Join Date
    Mar 2010
    Location
    Arnold, Mo
    Posts
    447
    Sorry that it took me so long to reply. When I arrived back on the scene the unit had new problems. Blower still was not running but now the reset button on the economizer was tripped. I reset it and the unit cycled off on high pressure. I found that 1 of the 2 condenser motors is bad. I replaced the motor and dual capacitor (10/10 mfd) on Friday. With the economizer reset and the new condenser motor, it seemed to operate fine. I waited for about 30 minutes and then I split. I am going back this afternoon to check on it again (and drop the bill off). Even if everything is fine, I am still concerned with the economizer reset being tripped. I will keep you posted.
    P.S. Something else that I found was that someone jumped out the board where the 5V fuse is supposed to be so there must have been a low voltage problem before me.

  10. #10
    Join Date
    Jan 2010
    Posts
    6,590
    Quote Originally Posted by flanders View Post
    P.S. Something else that I found was that someone jumped out the board where the 5V fuse is supposed to be so there must have been a low voltage problem before me.
    Or they did not have a replacement fuse. Are you planning on replacing it ?

  11. #11
    Join Date
    Mar 2010
    Location
    Arnold, Mo
    Posts
    447
    Quote Originally Posted by VTP99 View Post
    Or they did not have a replacement fuse. Are you planning on replacing it ?
    I don't know the reason why it is jumped out. I am going to put a fuse in but I want to rectify the problems at hand first.

  12. #12
    Join Date
    Jan 2010
    Posts
    6,590
    Quote Originally Posted by flanders View Post
    I don't know the reason why it is jumped out. I am going to put a fuse in but I want to rectify the problems at hand first.
    You could throw on a "lil popper 5 amp" till you find your problem. Provided the first one you try blows.

  13. #13
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    19,277
    Quote Originally Posted by pvc1984 View Post
    Nevermind that question...Forgot you need 24 volts to G on a carrier for the compressor to start.
    That must be a Resi thing. Not true on the RTU's.
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    2 Tim 3:16-17

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