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Thread: Blower speeds for heating and cooling are different

  1. #1
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    Blower speeds for heating and cooling are different

    Why does my ECM blower ramp up gradually for heat, but seems to switch on sharply for cooling? The graph below shows the pressure in the plenum first for a heating cycle, and then for a few cooling cycles later in the day.

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  2. #2
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    Maybe for comfort so it's not blowing cold air. In 'old fashioned' units there is a delay before the blower comes on in heat, this allows the heat exchanger to heat up to minimize blowing cold air in heat.
    I do a triple evac with nitro to remove non condensables.

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  4. #3
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    Quote Originally Posted by BBeerme View Post
    Maybe for comfort so it's not blowing cold air. In 'old fashioned' units there is a delay before the blower comes on in heat, this allows the heat exchanger to heat up to minimize blowing cold air in heat.
    And maybe preventing freezing the Evaporator on startup of the ac under low temperature conditions.

    Sent from the Okie state usin Tapatalk

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  6. #4
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    Weird how those graphs look like they are on regular notebook paper.

    Anyway, the idea in heat is to delay air flow so that the air coming out of the vents feels warmer faster.

    In AC mode this delay isn’t necessary and you want full air flow from the start to reduce freezing issues.
    "I think Quantum tunneling would work great... "

    "Call a technician for God's sake. Or we'll see you on the news or the Dark Side of the Moon."

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