Hi, hopefully someone can help out. Our towbar wiring is fitted with a pct volton 1220 relay which sends power to the caravan fridge once the engine is started. This does happen, but then within 10 seconds or so, the relay "clicks" off again. Then it seems to go on and off continuously - 10seconds on and 10 seconds off (approx).
I don't know why it should do this, perhaps the alternator on the car is weak? The battery is weak? The relay is faulty?
I have held a voltmeter accross the switched outlet of the relay and earth, it reads 13.5v when on and 0 when clicked off.
Any ideas ????
Sounds as though it might be faulty, the fridge isn't going to work that well with that kind of duty cycle. The way most of these work is to use the alternator warning light as a signal for the relay to turn on, so I'd expect it to be on 100% once the engine is running.
Have you tried it at increased engine rev's? Possibly it will come on continuously if the alternator output is higher with increased engine rpm.
The supply to the fridge is controlled by a voltage sensing realay in the back of your car. When the voltage reaches a predetermined voltage the relay passes voltage to the relevant pins, if the voltage drops below the value it turns off, this is correct function. However it would seem that the voltage set is too high and when the fridge starts up the load lowers the voltage to a lower level and turns itself off. you might find that increasing the revs will increase the voltage slightly and allow it to stay on, though it is more likely that the relay is faulty and neeeds replacing.
------------- Bill
For a licence dated 1997 or later you must add together the plated max weight of the caravan and trailer, if the total is 3500 or less you can tow it. You may even tow a caravan with a MAM greater than the cars unladen mass the restriction was removed in 2013
ive just had that problem myself, changed the relay with one i bought from towsure that has an adjustment on it for £9 something problem solved.hope this helps. if not can always return it.
Could also be something called "cycling", which means there's a voltage drop (under load) from the battery to the fridge. You need quite a "thick" cable for the live feed (minimum 66 strand, if I remember correctly)
Thanks for your suggestions. I have got hood of another relay of a different brand and was about to fit it after tea, but the heavens have opened. When the rain stops I will whack it in and see if it improves. Fingers crossed!
If not i suppose it could be the wires or something more sinister.
New relay fitted. A little tweaking on the adjustment dial and perfecto. It seems to be working great. After the engine is turned off, the relay clicks in and out a couple of times, then stays off. I think this must be just a little surge left after the alternator stops then ends up staying off within twenty seconds or so.
Hopefully this all seems good and job done and sorted!! Cheers guys