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Fan Switch

Discussion in 'Truck Talk' started by MYGIA, Jul 27, 2010.

  1. MYGIA

    MYGIA Rookie Expediter

    Does anyone know if you can have a driver controlled fan switch installed for a CAT 3126?
  2. greg334

    greg334 New Recruit

    I think you can.

    I read somewhere there was a setting for it in the ECM, but you may want to call cat and ask them if there is a kit for it.
  3. layoutshooter

    layoutshooter New Recruit

    I sure wish I had one on my truck. That is a very good tool to have.
  4. jcross

    jcross New Recruit

    Yes you can. I have a 1998 FL70 with the 3126 that I bought used and it has one on the dash. It looks like it was added aftermarket.

    Watching that temperature gauge drives me crazy though. It sure seems like I have to flip that switch on alot.....but when I do its runs the temperature gauge back down quickly.
  5. greg334

    greg334 New Recruit

    If you are watching the gauge too much, then maybe you have a problem?
  6. jcross

    jcross New Recruit

    I do feel like I have to watch the gauge too much. I haven't taken it to Cat yet to have them look over it (or have them plug it in).

    The engine is remanufactured and I had to have a new head gasket put on a while back and things have been relatively good. No bubbles in the coolant (I put the good stuff in) and it uses none. But before all of that I repalced the water pump, thermostat, temperature sensor, the sensor by the AC dryer, tensioner pulley, new belts, radiator (fill tank) cap, etc.

    I keep the radiator, CAC, AC condenser all cleaned out.

    I try to take pretty good care of things......

    BUT.......that switch is on the dash for a reason
  7. MYGIA

    MYGIA Rookie Expediter

    Thanks for the feedback. Much appreciated.:)
  8. MYGIA

    MYGIA Rookie Expediter

    I discussed this with the CAT dealer I use and trust. The service manager told me it could be done, but that he strongly recommended it not. He stated that the fan not only serves an important function of cooling the radiator, but it also helps cool the A/C compressor. To have a manual control switch that is used only when one deems necessary for the engine temperature, could lead to damage to the A/C. I decided to take his advice and leave things as they are.
  9. jjoerger

    jjoerger Seasoned Expediter

    We have one on our Mercedes MBE4000. It will turn the fan on so it stays on all the time. If you turn the switch off it goes back to working automatically. Never had to use it. Our fan kicks in right when it should.
  10. greg334

    greg334 New Recruit

    I never heard of it cooling the compressor, it provides a means for the condenser to remove some of the heat from the compressed gas while you are standing, idling or running really slow.

    The gas needs to get rid of the hear built up from the compression cycle, and the compressor may benefit from it by lowering the outlet pressure but I can only see this happening if the airflow it low across the compressor.

    The switch is a doable thing, the ecm will kick on the fan if there is an issue with either the coolant temps being high or if the condenser pressures are out of range - it is a backup for people who leave the fan off. The switch goes right to the ecm, not the fan.

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