Radiator fan on constantly

Discussion in 'Electrical & Interior - Security, ICE, Wiring Loom' started by Honeybadger, Oct 13, 2024.

  1. Hello peeps,

    in need of some help please. had a bit of a search but cant find the answer.

    turning the car on cold start and the radiator fan turns on full right away. would this be the thermostat being dodgy and now is stuck open?

    some help would be much apricated
     
  2. Hi,
    Radiator fan resistor maybe?
    214936501R
    Mine went off, and i had only second speed gear, pretty shit design.

    Cheers
     
    Honeybadger likes this.
  3. This post may give you some insights
    Cooling Fan Diagram - Megane III Technical - OZ Renault Sport

    If the fan relay (234) contacts have welded together due to overheating, this would cause your fan to run straight away. Pull the relay out (de-energised) and make sure open circuit between pins 3 and 5
     
  4. much apricated for the links and responds for zoto and pompon.

    looks like its going to be one pig of a job just to get to the fan relay and or the fan resistor! :weary:

    got the car out today to drive to work (I use the Clio as the daily) just to trouble shoot the Meg. still the fan at full tilt right away till switch off. but noticed it's also not getting up to temp... so I'm thinking thermostat needs replacing
    and possibly the temp sensor at the same time

    I will report back once I've had a go at it or given up and take it to my Renault specialist!
     
  5. Good luck
    Mind you if the fans running continuously whilst the engine is running I'm not surprised that you aren't getting up to temperature

    If the temp sensor was faulty, ECU logic might have a safety fall back of running all the time (better this then not coming on when over temp), but you would expect a warning light/message on the dash

    Difficult to diagnose without a DTC reader or ddt4all or similar
     
  6. Hey, sounds like it could be a faulty temperature sensor rather than the thermostat. If the fan kicks in full blast right away, even on a cold start, the ECU might be misreading the temperature. I'd check the sensor first before replacing the thermostat.
    And if you're swapping the thermostat, it's also worth checking the wiring and connections. Sometimes it’s just an electrical issue! :grinning:
     
    Seb RS likes this.

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