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#1146 DMC Motor Fan Problem?

Discussion in 'Roadster 2008-2012' started by 7racer, Jul 31, 2013.

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  1. BartJ

    BartJ early member

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    sometimes just unplugging/replugging the connector makes the error disappear for a while.
    these connectors are real crap for these amperages
     
  2. gregd

    gregd Active Member

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    Yes, and that applies to both ends of the cable. The fan end's .250 blade connectors are a lot more robust than the PEM end's tiny pins, but mine proved to be less than perfect too. I guess no connector ever is. Part of my work documented on the other thread suggests the two sets of wires should be paralleled (electrically connected together) upstream from the blower connectors, to increase robustness in the event of a partial connector failure.
     
  3. X.l.r.8

    X.l.r.8 Supporting Member

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    Weirdly my PEM motor had almost seized and was probably pulling a lot more power for some time. When I went to pick it up from recharging my AC it threw codes and obviously the PEM was hot. We threw it on the Ramp and blew air threw the PEM pan to see if we could get it moving and put penetrant on the bearing. It blew the fuse and while we were there we pulled all the plugs expecting something burnt, but it was all perfect. I was going to assume the plug would be burnt but it was not. I should also give a shout out to the SC that let me work on it while it was on the ramps and this was a 7:30 pm and made sure it would get me home to swap in a new fan. And didn’t even charge me for the AC recharge.
     
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  4. gregd

    gregd Active Member

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    Good data point! I've been measuring the current draw over the past month or so, and it's been very stable and sane. Peter at Gruber ran a quick amps vs volts test on a blower there, and my results match his, so the motor and bearings appear to be healthy. I opted to not replace the blower assembly, as that would tread into that magical "fixing something that's not broken" territory, where unforeseen consequences lay.

    If one suspects that the excessive current draw from the blower is the cause of a connector contact failure, it's easy to wire up an in-line ammeter, as the connectors under the car are easily accessed "F" style (0.250 blade), once the connectors are separated. Note that some of the LCD meters available online don't start working at under about 7 volts, and a normal top-off charge at 240v, 24 amps, 25C ambient, runs at between 6.5 and 7.0 volts, with each side supplying about 3.5 amps (6-7 amps or so total), and lasts about 7 minutes. There are meters that can use an external supply for running the meter's display for situations like this. Unfortunately, I didn't realize this when I bought mine, so I had to splice in a different meter that could work at the lower voltage for my monitoring.
     
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