Fridge problem

[RonD]

When running the fridge on 12v from the 12S socket I always understood the fridge supply came from the car when the engine's running.. In my Sterling Europa the fridge seems to be powered from a relay in the van. I arrived on site to hear a click,click noise and saw the red 12v led on the fridge blinking on and off. I hadn't switched the panel to car as I thought it unnecessary. Was the fridge running from the 'van battery via the relay? I'm confused, what's happening here?

 

[WatsonJohnG]

The fridge cooling does work from the car electrics via a relay.

If you have a voltage sensing relay it would explain what you saw/heard.

As the engine revs drop a little the voltage would allow the car relay to open and if the then revs rose slightly the relay would close putting the fridge on again

Inside the caravan is a habitation relay that switches all the interior 12V electrics off when it gets a signal from the 12S lead to the fridge.What you probably heard was the habitation relay cutting in and out.You can verify this by putting an interior light on in the van and starting the engine when at sufficient revs the light will go out under the influence of the habitation relay.

Now later Dometic and Thetford fridges also need a permanent 12V feed from the leisure battery to operate the electronic circuitry that controls the fridge.

The thermostat now operates when towing as well

Hope that helps

 

[RonD]

The fridge cooling does work from the car electrics via a relay.

If you have a voltage sensing relay it would explain what you saw/heard.

As the engine revs drop a little the voltage would allow the car relay to open and if the then revs rose slightly the relay would close putting the fridge on again

Inside the caravan is a habitation relay that switches all the interior 12V electrics off when it gets a signal from the 12S lead to the fridge.What you probably heard was the habitation relay cutting in and out.You can verify this by putting an interior light on in the van and starting the engine when at sufficient revs the light will go out under the influence of the habitation relay.

Now later Dometic and Thetford fridges also need a permanent 12V feed from the leisure battery to operate the electronic circuitry that controls the fridge.

The thermostat now operates when towing as well

Hope that helps

Thanks John, that helps a lot. I'll put a meter on the various pins and check things out. The relay IS the habitation relay as it's the first thing the van battery connects to and it's that which clicks. My 'van's a 1998 so a little out of date!

Regards,

Ron