306 S16 Thermo Fan Relay
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  1. #1
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    Default 306 S16 Thermo Fan Relay

    Hi,

    Under normal operation my S16's thermo fans run as they should but as soon as you switch on the air-con, the fans cut in and out every 10 or so seconds. This causes the engine temp to rise until the high speed fans kick in.

    I am led to believe they should run low speed constantly while the air-con is running.

    I'm assuming it must be a relay problem but can anyone tell me which one?

    Thanks

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  2. #2
    1000+ Posts HONG KONG PUGGY's Avatar
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    Could be as simple as a poor connection dropping in and out with the extra load. Check both connections on the relays behind the grill.

    Have you seen the tech explanation of the relays functions? it should also tell you what and where to look.

    There's heaps more info there too.

    http://peugeotlogic.com/workshop/base/workshop.htm
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  3. #3
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    Quote Originally Posted by HONG KONG PUGGY View Post
    Could be as simple as a poor connection dropping in and out with the extra load. Check both connections on the relays behind the grill.

    Have you seen the tech explanation of the relays functions? it should also tell you what and where to look.

    There's heaps more info there too.

    http://peugeotlogic.com/workshop/base/workshop.htm
    Thanks for that link HKPuggy although please forgive me as I am utterly hopeless when it comes to electrical work.

    But since the fans run as they should (low and hi speed) without the aircon, wouldn't that mean all connections are fine?

    Today I swapped the 2 green relays over to check if 1 was playing up but they both seem to work and activate low speed.
    I also know that the black relay works as it will change over from Low => Hi speed without any problems either.

    What I did notice though is that I will feel a "click" in the relays everytime the fans cut in and out while the air-con is on.
    Basically the fans will run for about 30 seconds, relays will click, fans will slowly spin down to a stop, the relays will click again and the fans will startup for another 30 seconds.
    Would this point to a Bitron Unit problem?

    cheers

  4. #4
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by Katana View Post
    Thanks for that link HKPuggy although please forgive me as I am utterly hopeless when it comes to electrical work.

    But since the fans run as they should (low and hi speed) without the aircon, wouldn't that mean all connections are fine?

    Today I swapped the 2 green relays over to check if 1 was playing up but they both seem to work and activate low speed.
    I also know that the black relay works as it will change over from Low => Hi speed without any problems either.

    What I did notice though is that I will feel a "click" in the relays everytime the fans cut in and out while the air-con is on.
    Basically the fans will run for about 30 seconds, relays will click, fans will slowly spin down to a stop, the relays will click again and the fans will startup for another 30 seconds.
    Would this point to a Bitron Unit problem?

    cheers
    Looking beyond the fans and relays, if they seem to work normally under control of engine temperature perhaps you could investigate the aircon system itself.

    If no expert by a long way on 306 aircon in detail but on a general level radiator fans and a/c condenser fans are usually activated by compressor head pressure. The theory being that more head pressure indicates the compressor is pumping harder, under normal conditions because it removing heat from the cabin which needs to dissipated by condenser therefore the fan speed ramps up.

    The trigger is usually a pressure switch located in hi side of the aircon refrigerant circuit. Many times in spare port of the receiver dryer, but in some cases well hidden. This switch I believe sends a signal to the bittron controller, which triggers the fan relays.

    If the aircon is not working properly (ie blowing cold forshort term running) I would investigate the refrigerant circuit.

    Consider this scenario. The aircon switches on and head pressure rises, the fan start. After running for a few seconds the head pressure drops and fans turn off. The pressure builds again and fans start etc . etc in a loop.

    Low refrigerant or partial high side blockage or tx valve can all cause this.

  5. #5
    1000+ Posts bluey504's Avatar
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    Katana the relays seem to work correctly, they 'click' when opening/closing. Nice work that you sussed that out, I've got a couple of 'alleged' electricians who still can't get that into their thick skulls! They are a solenoid powered switch, nothing more or less.
    The switching seems to be fine, it's just the signals they are getting are not as intended so as Rob suggests a visit to the A/C specialist is in order.
    Just watch out if he wants to check you out as his hands will be cold!

  6. #6
    1000+ Posts robmac's Avatar
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    Quote Originally Posted by bluey504 View Post
    K
    Just watch out if he wants to check you out as his hands will be cold!
    Or... hot, depending on which line he checks out!

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    Your feedback is appreciated gents, thanks.

    In regards to the A/C pressure, I am fairly sure it is running well. It will blow nice and cold all day long if I so desired, although chances are the engine will start to run hot with the low speed fans playing silly buggers.

    Besides that, it is good to know that the relays are not at fault. Always a good feeling moving onto the next step without handing over the hardearned!

    If you guys think it's the signal to the relay that needs attention, I will take a peek at the Bitron Unit (Fan Controller). Perhaps a couple of wires are rubbing loose or it just needs a tidy up and upon reading HKpuggy's workshop link, it seems that this might just be the source of my problems.

    Cheers.

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    Just thought I'd post up the solution incase any other members have a similar problem.

    It was the Bitron Unit after all!
    As simple as tidying up the connection due to corrosion on the metal connectors.

    Too easy.
    Thanks Robmac, Bluey and HKpuggy!

  9. #9
    1000+ Posts HONG KONG PUGGY's Avatar
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    That's excellent Katana.
    All the better because as you said, your first real attempt at fixing 'leccy stuff. Must be pleased with yourself. Hope you had a to celebrate
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  10. #10
    1000+ Posts bluey504's Avatar
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    Default It's the simple things in life/automobiles that get you!

    Well done Katana! It really is the simple things that get you, the 'bleeding obvious'. What you discovered was that the corrosion increases the resistance from the Bitron Unit so the signal chops between on/off as it reads high resistance each way and therefore has a narrow band in which it operates.
    The extra load means that the unit cuts in early when going up and drops out early when going low. This gives the relays a greater cycle rate and can lead to failure but the clever Frog you are solved it!
    As my late father always said when someone had a Edison/lightbulb moment, "Take a Pound from the till and the rest of the day off." Had to see the look on the Japanese engineer when it happened when worked for Nissan, he reckoned it was beyond priceless!

    Rob I'm more concerned if the AC specialist is moonlighting as a 'bloke' medical specialist type regarding hand warmth!

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    That's a great description Bluey, I was actually wondering why the corrosion would cause signal problems.

    I think it's about time I brushed up on my electrical work! I told myself 6 years ago I would never take my car to the mechanics again and while I'm all over the mechanical side of things, when it comes to the wires, I'm clueless.

    Thanks again gents.

  12. #12
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    Just so the thread is "more" complete, you could describe where the Bitron unit is (ie. left guard, etc.) to help other not so knowledgeable troubleshooters.
    Regards,

    Simon

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