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    ellis1980's Avatar
    ellis1980 Posts: 1, Reputation: 1
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    #1

    Nov 7, 2017, 07:40 AM
    Low voltage fuse blows when heat is turned on
    My ac works great but the moment I turn the tstat to heat it blows the low voltage fuse. I disconnected the tstat and ran a new tstat wire and the problem continues. Any suggestions on trouble shooting this issue. Thanks
    talaniman's Avatar
    talaniman Posts: 54,327, Reputation: 10855
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    #2

    Nov 7, 2017, 01:06 PM
    You can watch a few YouTube, but you will need an ohmmeter, and know how to use it to find a short that blows your fuse. It can be a wire or component on most furnaces. You didn't give your make and model number and while the process is basically the same there are differences in components and wiring.

    For the cost of components just changing parts is an expensive hit or miss but viewing the videos will help you decide if it's something you want to try, or call a trained licensed tech to solve your issue.

    No error codes?

    ***Poking around a live furnace can be dangerous and costly for a novice.****
    Stratmando's Avatar
    Stratmando Posts: 11,188, Reputation: 508
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    #3

    Nov 15, 2017, 08:21 AM
    Either the Heat wire is shorted, or Contactor/Relay Coil is shorted.
    Try removing the low voltage wire at the coil of heat contactor, and try again, if it doesn't blow, it is the relays coil. Good Luck
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