Erratic Fridge,

digger58

Anybody any ideas on this, after 4.5 Hrs last week I finally found the source of the faults in my 12 volt supply, one burned connection at the distribution board and a blown fuse on the 12V + from the alternator, fridge now works on 220V , 12 V and gas, only problem seems to be that the mains operation seems to be erratic, will start fine and run for ages but then suddenly cuts out and light flashes, will switch to gas if it's available, why is this? Are they very sensitive to fluctuations in mains supply, last week when away would not work on mains but the supply was very suspect, what range of supply do they need to work? Its an Electrolux (Dometic) RM6505, Book says it will revert to gas if voltage is too low, any idea what "too low"? is Thanks in advance.

Manual here.

Sounds like a wiring issue. Have you got air con?

For electricity supplied at Low Voltage by ESB Networks, the nominal standard is 230 Volts, 50Hz.. ESB Networks undertakes to deliver single phase electricity within a voltage range of 207 Volts to 253 Volts.

UK run 10V higher iirc so if it's a UK fridge then 217V - 263V. A basic fridge wouldn't be bothered by undervoltage at all (although the switch bulb would dim) and overvoltage would handle pretty well for a short interval. I'll have a closer look at yours in a while.

moodrater

Looks like control board issue:
http://forums.motorhomefacts.com/49-tech-mech-chat/30932-aes-fridge-problems.html

Would be cheaper to fit a mains to 12V supply if it works ok on 12v.

digger58

Thanks for the replies, I have the wiring diagram and manual, I am leaning towards fluctuation in current, It seems to work perfectly sometimes and then suddenly seeks gas, this is as it's supposed to do if the mains drops, I am interested in what are the tolerances for the current? From working on it for the last while I feel the control box is OK, everything else is now working. How much of a current drop will throw out the mains connection? It is designed to switch to gas if the voltage drops, my question is what kind of a drop will trigger the AES to switch to gas?

I just posted the wiring doc for the rest of us.

Depends on your supply wire gauge, and other running loads. 10's of kW would be needed on a standard setup.
It's a resistive load you shouldn't get fluctuations, the power factor would be pretty high. Unless your are running VSD on the same supply or some-at.
Might be your EHU is too long and the gauge too small.

Easiest thing to do is stick a multi meter in the socket set to record min/max and babysit it til the gas kicks in and work from there.
Still haven't taken a proper look at the electron plan though so I may have to correct myself later.

Aidan_M_M

control board failures are all too common on those , it was part of the reason the next evolution of them had a manual override.

digger58

Sir Liamalot wrote: »

I just posted the wiring doc for the rest of us.

Depends on your supply wire gauge, and other running loads. 10's of kW would be needed on a standard setup.
It's a resistive load you shouldn't get fluctuations, the power factor would be pretty high. Unless your are running VSD on the same supply or some-at.
Might be your EHU is too long and the gauge too small.

Easiest thing to do is stick a multi meter in the socket set to record min/max and babysit it til the gas kicks in and work from there.
Still haven't taken a proper look at the electron plan though so I may have to correct myself later.

OK I give up, I was never any good at scrabble, VSD,EHU (presume that's Electrical hook up)! I'm not an electrician. All wiring is what it came with so nothing has changed. No other loads on the supply. My meter hasn't that function either! In layman's terms, what sort of drop would trigger the fridge to seek gas?

Sorry Digger,

A VSD is a variable speed drive, a type of industrial induction motor, they wreck havoc on sine waves (electricity supply stability).

A 2000Watt load or greater would very briefly drop the supply 25V for milli-seconds, I doubt the fridge is that sensitive, so it would probably have to be an order of magnitude greater and I think that's unlikely. A dodgey/badly regulated petrol electric generator could also do it.

An EHU is the motorhome term meaning electrical hook up.

If it was very long and or very thin cable then you might have enough voltage drop in the camper to push you under the threshold if you also turn on a large load like a hair-dryer, electric oven, microwave, kettle, air-con sortov thing. [Edit] Similarly if you are on an elaborate underwired ring main in a site with neighbours running heavy loads this would also affect the power quality and cause voltage dips.

Could also be a lose connection that's carbonised from arcing and creating a high contact resistance.

Does the fridge 12V side have a thermostat?

Aidan's the expert by the way.
Stick a multimeter in the socket beside what your fridge is in, set it to >250VAC in the phase sockets (lower two of the three pin receivers...the top one is the earth) and take a reading next time your fridge changes over, if it's over ~215V at the time then look for a problem elsewhere.

195V is the lower limit it says here, it doesn't specify if that's for the AES version though.

Link

Maplins do a cheaper one.