Just returned from 2 weeks in France .... great time, apart from fridge not working on towing.
12v LED indicator clicks on and off (constantly) when engine on and can hear just clicking noise in back of car (not sure if relay knackered?).
Any ideas? We had problems with 12v circuit previously and Dometic engineer attended and replaced circuit and it worked for a bit, but now not working again (although this time it does click on and off, but just won't stay on all the time). Driven 2000 miles with it doing this and worried it will damage it.
Does it sound like fridge or electrics up the shoot?
By a strange coincidence I have just returned from a friends house who has exactly the same symptoms as you. In his case the caravan is new and he has just had the grey socket added to the car electrics. He wanted me to try my car plugged into his van to see if it was van or car that was the problem.
The fridge worked perfectly when connected to my car so it must be a problem with the grey socket electrics in his car - you could hear the relay in the car clicking on and off, wonder if its faulty?
See what others think. I was thinking of doing same (checking someone else's car on van) but haven't found anyone yet in right place at right time to try it out.
Hi Ben , does sound like the car end to me , possibly how the relay has been wired in or how the 12s socket has been wired to the relay/car chassis. The relay ( voltage sensing type ) should click off when the voltage coming from the car battery drops below a set limit , this is to stop the car battery being flattened by the fridge ( like when the car engine is stopped or when the engine is idling and not producing enough voltage to supply the fridge ) . It sounds like the relay is reaching this limit as your driving , so either the relay is faulty or the output to the relay from the car battery isn't enough , this could point to either a failing alternator or a faulty car battery .
The other type of relay ( the one i have fitted to my car ) supplies the fridge only when the car engine is running , if you have this type then it's faulty or not wired correctly .
Both relays should have a heavy duty wire going to the battery with a fuse inline . Have a look at this wiring info for the 12s socket connections http://www.volvoclub.org.uk/towbar_electrics.shtml i would have thought your 12s socket/plug is wired to the later ( 1999 Pin Allocation ) spec . If you check the grey cable coming into the boot area from the 12s socket , the red wire should be going to the relay and the black wire should be going to the car chassis ( earth ) separately from any other wires ( ie so it has it's own earth connection point ) .
Hello Ben,
Just had the same thing.
Took the problem to auto electrician and he said that the battery wasn't charged enought tho keep the fridge going.
Once the battery was fully charged then the clicking on and off stopped.
I didn't fully understand the reason except that even though the battery appears full it actually hasn't got enough power in it to keep the fridge going. As you drive along with the fridge on there is not enough charge going back into the battery. So it seems that the fridge takes more than the alternator can give back.
So as the fridge needs the full battery to work it keeps clicking on and off. He suggested that a couple of times a week to hook up and charge the battery for a couple of hours.
Ben
I had a similar problem when I purchased a new van. I think the story goes like this.
The fridge is on a circuit which switches off when the engine stops, to ensure it doesn't drain the car battery. To do this, it detects the voltage on the input to the relay (which increases as the alternator starts charging).
The problem with this arrangement is that the relay is normally in the boot of the car, which can be a long way from the battery. Hence, the relay sees a voltage drop between the battery, and the point at which it controls the circuit for the fridge.
When the fridge draws current, it causes a voltage drop. (The bigger the fridge, the more the voltage drop). This can cause the relay to trip out, which removes the power from the fridge. Of course, at this point the power drain becomes negligible (As the fridge is now switched off) and hence the voltage drop disappears, and so the relay sees the full voltage again, so it switches back on etc. This leads to the cyclic clicking you were hearing.
On my car (which had Witter electrics I seem to remember) there was a sensitivity adjuster on the relay unit, which allowed one to adjust the voltage at which it switched. By adjusting this, the problem was solved.
Quote: Originally posted by brendajorsler on 11/09/2005
Just had the same thing. Took the problem to auto electrician and he said that the battery wasn't charged enought tho keep the fridge going. Once the battery was fully charged then the clicking on and off stopped.
That doesn't make much sense to be unless the alternator is too small or faulty.......
Once the engine is running, the electrics should all be powered by the alternator - under very heavy loadings the battery may have to make up some shortfall with the engine ticking over. But certainly there should not be an issue whilst driving.
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Topic: Fridge or relay or fuse?
