Clicking fridge relay

spk
spk Forum Participant Posts: 406
edited June 2016 in Caravans #1

lunar quasar 2015

 

when the car electrics are plugged in but car switched off you can hear a relay clukubg rapidly from the fridge vents, this stops when car running. I have not noticed this before. Anyone any ideas is it normal or a fault. Mentioned do dealer when it had
recent service but they came out with some nonsense about it beng wired with alko stability control, not convinced they even checked itm

Comments

  • roylovelock
    roylovelock Forum Participant Posts: 20
    edited June 2016 #2

    the alko atc system clunks once only when you plug into the car. Are you sure you dont have your fridge set to gas and it is trying to light the gas?

  • spk
    spk Forum Participant Posts: 406
    edited June 2016 #3

    sorry for late reply.

    no its definitely set on 12v and definitely a relay clicking rapidly

  • EmilysDad
    EmilysDad Forum Participant Posts: 8,973
    1000 Comments
    edited June 2016 #4

    Sounds like it could be the caravan's habitation relay which is switched via your car's split charge relay. Find the car's split charge relay and they can usually be tweaked to sort the problem that you have.

  • Snowy1
    Snowy1 Forum Participant Posts: 263
    edited June 2016 #5

    I agree with MM, sounds like your towcar is fitted with a Voltage Sensing Relay (often referred to as a split charge relay), these relays control the 12 volt power supply to the caravans's fridge, habitation & changeover relays, they are renound for switching
    back and forth after the towcars engine has been terminated until the voltage stableises. As MM says, you can often cure the problem by adjusting the voltage trigger point as they are adjustable.

  • Snowy1
    Snowy1 Forum Participant Posts: 263
    edited June 2016 #6

    A way of confirming if this is the cause is to switch on one of the caravans' 12 volt interior lights, if said light flashes on & off in time with the clicking noise this will confirm the cause.

    Colin

  • spk
    spk Forum Participant Posts: 406
    edited June 2016 #7

    great advice gentlemen I shall test the theory in the morning when I hook up. Then if its that find the pesky relay and give it a dam good thrashing

  • markflip
    markflip Forum Participant Posts: 177
    edited June 2016 #8

    The relay is clicking because the battery voltage from the car (particulalry if it's just been running) is high enough to activate the relay, but the current drawn when it does, drops the voltage to below threshold so it clicks off, then the battery voltage
    'recovers' up above threshold, relay clicks on and the cycle is repeated.....

    As Snowy1 says, increasing the threshold voltage of the charging relay will cure this issue.

  • spk
    spk Forum Participant Posts: 406
    edited June 2016 #9

    thanks for info.

    I could not test with hab light on as when car is plugged in it disables the control panel. Is this adjustment one for my tame towbar technician then ??

  • EmilysDad
    EmilysDad Forum Participant Posts: 8,973
    1000 Comments
    edited June 2016 #10

    thanks for info.

    I could not test with hab light on as when car is plugged in it disables the control panel. Is this adjustment one for my tame towbar technician then ??

    Once you've found the relay in the car, the pot on the side is obvious, just turn it slightly till any clicking stops .... though I'm sure your towbar fitter would do it for you if you're not sure

  • Snowy1
    Snowy1 Forum Participant Posts: 263
    edited June 2016 #11

    These Voltage Sensing Relays (VSR's) are very troublesome in any case as they periodically need readjusting as the condition of the towcars battery deteriorates which causes the voltage to drop off faster. I no longer fit them for said reason and that they
    are not compatterble with Smart Alternators which are now fitted to many cars. I use a my own design module which has a 555 chip within it, this module controls the fridge supply by allowing the towcars engine to slightly warm up and put the bulk of the cranking
    power back into the towcars battery before it switches the power through to the caravans' fridge, this delay can be adjusted between 1.75 and 3.5 minutes, the module is compatterble for towcars with auto stop/start. They never fail!

  • spk
    spk Forum Participant Posts: 406
    edited June 2016 #12

    great info many thanks to all. I think I know were it is but if I cant find it I will ring towbar chap who I have a good relationship with.

    incidentally my car is stop start

  • spk
    spk Forum Participant Posts: 406
    edited July 2016 #13

    thanks gentleman you were right. I found relay turned it clockwise until clicking stopped. However is it correct that when car is off the ATC light is still illuminated and the control lights on the fridge are lit ??

  • Snowy1
    Snowy1 Forum Participant Posts: 263
    edited July 2016 #14

    thanks gentleman you were right. I found relay turned it clockwise until clicking stopped. However is it correct that when car is off the ATC light is still illuminated and the control lights on the fridge are lit ??

    The Al-Ko ATC LED light (red or green) on the caravans' A-frame remains lit when the towcars engine is terminated. It only goes out then the caravan is unpluged from the towcar, in other words, it is fed by the permanent supply from the towcar, 12s pin 4
    or europlug pin 9. Not sure about the fridge as there are so many different types of fridges now fitted to caravans.

    Colin

  • Tinwheeler
    Tinwheeler Forum Participant Posts: 23,155 ✭✭✭
    10,000 Likes 1000 Comments Name Dropper
    edited July 2016 #15

    The control panel of the fridge is powered by the 12v leisure battery.

    The fridge cooling element operates on 12v only via the car battery and towing electrics when the engine is running.

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