Electrical Dometic fridge not working??

[mikerezny]

If the reading is zero then your element is open circuit and requires replacing.

Hi,
I think you mean if the element reads high resistance then it is open circuit and needs replacing. Zero resistance would indicate a short circuit element. Unlikely in this case since a short circuit element would be tripping the RCD unit.

The test is actually very easy to do. Turn the fridge to off, measure the resistance across the active and neutral pins of the fridge 240V plug. It should read high resistance. Now turn the fridge to 240V and repeat the measurement. If the fridge has a 175W element, the resistance across the plug should be about 330 Ohms.

take care
Mike

 

[Boots in Action]

Hi,
I think you mean if the element reads high resistance then it is open circuit and needs replacing. Zero resistance would indicate a short circuit element. Unlikely in this case since a short circuit element would be tripping the RCD unit.

The test is actually very easy to do. Turn the fridge to off, measure the resistance across the active and neutral pins of the fridge 240V plug. It should read high resistance. Now turn the fridge to 240V and repeat the measurement. If the fridge has a 175W element, the resistance across the plug should be about 330 Ohms.

take care
Mike

Not necessarily @mikerezny . That test will only confirm that there is a problem in the wiring or switching of circuit to heating element and not just the heating element. The fault could then be wiring of 240 volt line not connected or loose wire, or bad/corroded connection at switch (or wire off switch - unlikely) or heating element failure causing open circuit. To check the heating element alone, it would be best if the multi-meter probes are placed across the connector/connection point where the 240 volt line connects to the heating element line. You do not then have to worry about switching position. Usually accessible and easy to locate (usually marked too) through the bottom vent space. If heating element shows resistance as @mikerezny quoted, then the problem is in the switching mechanism or 240 volt line.

MAKE SURE 240 VOLT LINE/LEAD TO VAN IS NOT ONLY OFF BUT ALSO DISCONNECTED. 240 VOLTS AC IS DEADLY .

 

[mikerezny]

Not necessarily @mikerezny . That test will only confirm that there is a problem in the wiring or switching of circuit to heating element and not just the heating element. The fault could then be wiring of 240 volt line not connected or loose wire, or bad/corroded connection at switch (or wire off switch - unlikely) or heating element failure causing open circuit. To check the heating element alone, it would be best if the multi-meter probes are placed across the connector/connection point where the 240 volt line connects to the heating element line. You do not then have to worry about switching position. Usually accessible and easy to locate (usually marked too) through the bottom vent space. If heating element shows resistance as @mikerezny quoted, then the problem is in the switching mechanism or 240 volt line.
MAKE SURE 240 VOLT LINE/LEAD TO VAN IS NOT ONLY OFF BUT ALSO DISCONNECTED. 240 VOLTS AC IS DEADLY .

Hi,
I want to ensure that the 240 wiring in the fridge is not touched by inexperienced people. This is dangerous.

Measuring the resistance at the plug ensures that the fridge is indeed unplugged and cannot possibly be connected to 240V. Measuring the resistance at the plug does not need to be done by a qualified electrician and will not void the insurance on the van. Measuring the resistance with the fridge switched off and then on tests whether the element is connected correctly, that the switch works, and the element the correct resistance.
This simple test can be done quickly and safely and does not entail disturbing the fridge in any way.

It would not be the first time that someone has been electrocuted by following the simple instruction of disconnecting the power lead and then diving in to the appliance whilst it is still active. They did disconnect a plug but actually disconnected the plug from a different appliance.
Made this mistake repairing a valve radiogram when I was 15 years old. A lesson I have never forgotten

So, pulling out the 240V supply to the van solves this problem. Think again. It doesn't. We do not know how vans owned by other people are wired.
People have been caught. Pull out the 240V supply from the van. Dive in, nothing to worry about. Opps, got a hit! Forgot the van has an inverter, didn't think to switch it off and some power points are actually live. Not connected through an RCD, so absolutely no earth leakage protection.

I will not be giving ANY advice regarding internal 240V wiring. We do not know the level of competence of those asking for advice or those who will read these posts in the future.

After over 50 years in the game, this is the first test I would do.

After this extremely simple first test that I have carefully suggested, the OP can determine how next to proceed.

take care
Mike

 

[Boots in Action]

Hi,
I want to ensure that the 240 wiring in the fridge is not touched by inexperienced people. This is dangerous.

Measuring the resistance at the plug ensures that the fridge is indeed unplugged and cannot possibly be connected to 240V. Measuring the resistance at the plug does not need to be done by a qualified electrician and will not void the insurance on the van. Measuring the resistance with the fridge switched off and then on tests whether the element is connected correctly, that the switch works, and the element the correct resistance.
This simple test can be done quickly and safely and does not entail disturbing the fridge in any way.

It would not be the first time that someone has been electrocuted by following the simple instruction of disconnecting the power lead and then diving in to the appliance whilst it is still active. They did disconnect a plug but actually disconnected the plug from a different appliance.
Made this mistake repairing a valve radiogram when I was 15 years old. A lesson I have never forgotten

So, pulling out the 240V supply to the van solves this problem. Think again. It doesn't. We do not know how vans owned by other people are wired.
People have been caught. Pull out the 240V supply from the van. Dive in, nothing to worry about. Opps, got a hit! Forgot the van has an inverter, didn't think to switch it off and some power points are actually live. Not connected through an RCD, so absolutely no earth leakage protection.

I will not be giving ANY advice regarding internal 240V wiring. We do not know the level of competence of those asking for advice or those who will read these posts in the future.

After over 50 years in the game, this is the first test I would do.

After this extremely simple first test that I have carefully suggested, the OP can determine how next to proceed.

take care
Mike

Fair comment @mikerezny. You never really know what abomination of wiring has been modified by others.

TOTALLY DISCONNECTING ANY LEAD TO VAN, BE IT 240 VOLT AC OR EVEN 12/24 VOLTS DC, IS ABSOLUTELY PRIORITY. INVERTERS STILL SWITCHED ON AND CONNECTED TO BATTERY/IES COULD BE ANOTHER SOURCE OF POTENTIAL LETHAL POWER. I guess one should work on the lowest common denominator of knowledge or incompetence!!

If you can read and operate a multi-meter, then normal safety thinking should be present. How come you did not follow safety procedures when working on valve radiogram? Was it the power unit for the valves or the 240 volt motor for the turntable drive??

 

[Drover]

I try to advise in these type of fridge cases removal of element and check it on bench, the usual 240 disconnects of course, if the element is okay and further checks required its a Sparky job, I may do it myself but never advise anyone else and if anyone doesn't know how to use a multi meter then certainly seek a qualified person..................... 12v is one thing with a meter 240 entirely another... a power point is way more dangerous than any of my firearms.

Made this mistake repairing a valve radiogram when I was 15 years old. A lesson I have never forgotten

I feel a bit of Deja Vu there @mikerezny , did the same thing about the same age trying to get the old radiogram working, my hand found a hot spot. I too had pulled the wrong plug, bed lamp instead of radio, painted the plug with a fancy fluro paint after that........ 1969 was a good year for finding out more about this form of steam................. If my Dad would have bought me a transistor radio and a portable record player I would have missed the sizzling experience.

 

[mikerezny]

Fair comment @mikerezny. You never really know what abomination of wiring has been modified by others.

TOTALLY DISCONNECTING ANY LEAD TO VAN, BE IT 240 VOLT AC OR EVEN 12/24 VOLTS DC, IS ABSOLUTELY PRIORITY. INVERTERS STILL SWITCHED ON AND CONNECTED TO BATTERY/IES COULD BE ANOTHER SOURCE OF POTENTIAL LETHAL POWER. I guess one should work on the lowest common denominator of knowledge or incompetence!!

If you can read and operate a multi-meter, then normal safety thinking should be present. How come you did not follow safety procedures when working on valve radiogram? Was it the power unit for the valves or the 240 volt motor for the turntable drive??

Hi,
I was about 15 years old! In 9th or maybe 10th grade at school.

I was stuck in the corner behind the radiogram and asked the elderly lady to switch the power off for me. She switched off the power to a table lamp by mistake. It didn't occur to me to double check, just assumed it was safe to pull the chassis out. Fortunately I survived and that lesson was enough to keep me safe from then on.

take care
Mike

 

[chartrock]

I got my jolt during my apprenticeship (as a fitter) on the aircraft carrier “ Melbourne”. Down in one of the stern tubes, about as far away from sunshine as you can get. Someone asked me to pass a 6ft bar up to them. I just picked it up and passed it over my shoulder, straight through a light bulb. Instant blackness, I thought I was dead, but the abuse that followed from everyone else working in the ship convinced me I was OK, but now know how dark it can be with absolutely no light. I was not game to move because there was little to no room around the propellor shaft and no easy access to get out. Fun times.

 

[mikerezny]

I try to advise in these type of fridge cases removal of element and check it on bench, the usual 240 disconnects of course, if the element is okay and further checks required its a Sparky job, I may do it myself but never advise anyone else and if anyone doesn't know how to use a multi meter then certainly seek a qualified person..................... 12v is one thing with a meter 240 entirely another... a power point is way more dangerous than any of my firearms.



I feel a bit of Deja Vu there @mikerezny , did the same thing about the same age trying to get the old radiogram working, my hand found a hot spot. I too had pulled the wrong plug, bed lamp instead of radio, painted the plug with a fancy fluro paint after that........ 1969 was a good year for finding out more about this form of steam................. If my Dad would have bought me a transistor radio and a portable record player I would have missed the sizzling experience.

Hi, I think this lesson was in 1967 or 68. My first stereo was an old mono valve radiogram that I was given and got working. I fitted a stereo cartridge found an old valve mantle radio, got that working as well. Salvaged a 12" speaker from somewhere and built a box for it. So the radiogram was one channel and the mantle radio and large speaker was the other channel. First single I bought was Legend of Zanadu by Davey Dee Dozey Beaky Mick and Tich. First LP I bought was the Seekers. You may remember that the speakers in early radiograms did not have magnets. They had an electromagnet that was powered by feeding the high tension 400V rail though a coil wound around the speaker to provide the magnetic field.

Eventually saved up enough money from delivering papers to buy a 7 transistor Astor radio. Really upmarket, but, truthfully, nowhere near as exciting as going to bed and trying to listen to the top 40 countdown from 2UE on my own home-made crystal set. Had an aerial running out of my bedroom up to the highest point I could climb on our mango tree. Maryborough, Qld was a long way from Sydney 2UE, but, on a good night, I could get Brisbane and Sydney stations on my crystal set. No problems getting stations on the Astor.

take care
Mike

 

[Drover]

Oh Yeah @mikerezny , mine was a phonogram ?? anyway record player and radio with a few speakers that once lived in a huge cabinet which I dismantled and reboxed, it would pick up 2SM from Sydney and we were south of Lake Illawarra, it was desperately needed as my crystal set just couldn't pull in 2SM.. Any old valve radio I would pounce on for valves and keep them in modified egg cartons, even had the odd punch up when fellas just wanted to throw them at a wall or tree's, duds okay but not good ones............................ hence why everyone thought I would be a sparky or rad tech, not someone who would shoot and blow things up and other things.............
Early lesson........ when a plug on a lead is broken cut both off if not replacing straight away.............. Phone lines can give a boot especially when the operator cranks the handle.

Not off topic just whiling away the time while we wait for the grand news that the problem is solved.........................

 

[mikerezny]

Phone lines can give a boot especially when the operator cranks the handle.

Hi,
yes magneto phones can give you a jolt.

But not as much as an insulation test from the test technician at the telephone exchange. It was during the huge floods in Maryborough around 1970. They drafted us technicians in training to go out with the cable guys to help restore the phones out of action because the cable pits were full of water and moisture was getting into the cable joints. Unlimited overtime!!!! Wet as a shag, sitting on the side of the pit, shorts, bare feet dangling in a pit full of water. Normally, you ask for a cable test, wait 30s and reconnect to talk to the desk. The test technician, ensures that he has finished applying the 400v insulation test within 20s, giving a 10s margin to avoid getting zapped. Didn't happen. started reconnecting after 30s and got 400v dc and sitting with my feet in water, I got a reasonable earth! Boy, did I jump! The cable guys had a good old laugh. One said, now you know what it is like, I am sure when you are on the desk, you will certainly remember.

I did remember, and, since I did that stint in the floods, I got on very well with all the linies and cable guys. Eventually, I was their #1 choice for cable and line testing since I knew what it was like being out in the field.

I don't believe I was even 17 since I am pretty sure I couldn't yet drive the work vehicles.

take care
Mike

 

[Drover]

Bit like testing the connections on a portable sound powered phone, as the new bloke was twisting on the wires you would give it a crank, not 400 but enough to have them jumping, now they would put you in jail and valuable lessons lost.

 

[Roadhouse]

So if you do use a multimeter to check the element as suggested by @Drover please make sure the 240V supply is disconnected from the van. Set the multimeter to ohms and place your probes on either terminal of the element. If the reading is zero then your element is open circuit and requires replacing. You ‘may’ need to disconnect the element from the wiring as there may be resistance in the circuit but I reckon @Drover or @Boots in Action may have done this a few times and can offer advise.

Element fine at 286 ohms (vs 293 ohms normal) so will now check selector switch...

 

[Boots in Action]

Element fine at 286 ohms (vs 293 ohms normal) so will now check selector switch...

@Roadhouse , well at least there is some progress now. It could also be a faulty thermostat which is just as likely as faulty switching. Unfortunately, I think you will have to remove fridge to check these items. Good chance to now fully insulate all interior of fridge cavity for better operation. Don't forget to properly reseal/replace the front section of fridge to prevent unwanted gases (when operating on gas) from entering internal areas of van. Please keep us informed. We all like to hear of successful outcomes. As for the warnings, please ensure you have NO 240 VOLT POTENTIAL ANYWHERE whilst working on fridge.

 

[Roadhouse]

@Roadhouse , well at least there is some progress now. It could also be a faulty thermostat which is just as likely as faulty switching. Unfortunately, I think you will have to remove fridge to check these items. Good chance to now fully insulate all interior of fridge cavity for better operation. Don't forget to properly reseal/replace the front section of fridge to prevent unwanted gases (when operating on gas) from entering internal areas of van. Please keep us informed. We all like to hear of successful outcomes. As for the warnings, please ensure you have NO 240 VOLT POTENTIAL ANYWHERE whilst working on fridge.

yes isolated everything to be safe...

Well will indeed need to pull out the fridge to check thermostat and selector switch but the mrs and kids are going away in the van for 2 weeks from the weekend (ah the peace and quiet!) so will check these upon their return. Don't want to f anything up beforehand and not have the fridge available to them as it is working fine on gas.

Will need to work out how to move fridge forward without disturbing the gas line. That doc from @mikerezny had some info so should be ok.

Stay tuned for another exciting episode...

 

[Boots in Action]

yes isolated everything to be safe...

Well will indeed need to pull out the fridge to check thermostat and selector switch but the mrs and kids are going away in the van for 2 weeks from the weekend (ah the peace and quiet!) so will check these upon their return. Don't want to f anything up beforehand and not have the fridge available to them as it is working fine on gas.

Will need to work out how to move fridge forward without disturbing the gas line. That doc from @mikerezny had some info so should be ok.

Stay tuned for another exciting episode...

Removing the fridge is really a simple job if you take your time. There are manuals to assist. Unfortunately it will require you (or someone in the know if necessary) to disconnect both the 12 volt and 240 volts connections AND the gas line. Always use TWO proper fitting spanners when undoing gas unions and know how to test for leaks when re-connected. I have a Thetford which has the gas connection readily accessible at the rear, but from memory when working on friend's Dometic, the connection was at the top and was only accessible when fridge moved forward. A few screws at the front and a couple at the back hold the fridge in place. Good luck and stay safe.

 

[Roadhouse]

Removing the fridge is really a simple job if you take your time. There are manuals to assist. Unfortunately it will require you (or someone in the know if necessary) to disconnect both the 12 volt and 240 volts connections AND the gas line. Always use TWO proper fitting spanners when undoing gas unions and know how to test for leaks when re-connected. I have a Thetford which has the gas connection readily accessible at the rear, but from memory when working on friend's Dometic, the connection was at the top and was only accessible when fridge moved forward. A few screws at the front and a couple at the back hold the fridge in place. Good luck and stay safe.

cheers.

Have a mate who is a plumber so he can muck around with the gas connection. My father and brother are both Sparkys so have that angle covered too ! Battery disconnected and nothing else powering the van at all. All switches off etc. No inverters...

 

[Drover]

Non drama removing the fridge, its on page 9 but just read how you fit one and do it in reverse, disconnecting the 240v can be tricky as you may break a nail when you pull the plug out of the PP and pass it thru the hole in the wall, not dangerous one little bit, they often have 2 screws in the floor at the front and 2 in the back, you may have to remove any baffles fitted at the rear and as Boots said 2 spanners on the gas joint and don't force or bend, use plumbers gas fitting goo when connecting back up, again firm but gentle, fuel line spanners are ideal, and when all finished spray join with mild soapy water and turn on gas, if it bubbles its not done up.....here's the installation manual for your fridge.

Good time as Booties said to give it all a good tidy up, improve insulation and improve the air flow in and out at the back..... Oh just thought before you pull the fridge out undo the the chimney vent on the outside wall, remove the plastic shroud and the screw holding the top of the chimney, it may fall inside but no problem....

 

[Roadhouse]

Yeah will be a bit fiddly. As boots said gas connection looks to be on top (manual shows it at bottom of fridge nicely accessible via the rear vent but not to be...)

plug cord seems to go down under fridge (see pic below - black cord disappearing into orange expanding foam bottom left of fridge) and presumably pops up again somewhere to a PowerPoint (manual says position the powerpoint/plug 150mm up from bottom so accessible from rear vent but alas, again!).

Bit of a dogs breakfast back there so a bit to disconnect.

it also looks like mounting screws at back aren’t really screwed in, nor are ones on front of fridge at top. Something to rectify when reinstalling. Maybe stripped in the wood they are screwed into.

 

[mikerezny]

Hi,
have you tried my suggestion to measure the resistance across the active and neutral pins of the power plug with the fridge switched to operate on 240V?

Seems like you are using the wrong manual.
What model fridge have you got. If it is an RM2350, the manual for that fridge clearly states in the section on gas connection that it is connected at the top.

This is shown on these two photos. The connection is on the LHS at the end of the selector switch.

take care
Mike

 

[Roadhouse]

Hi,
have you tried my suggestion to measure the resistance across the active and neutral pins of the power plug with the fridge switched to operate on 240V?
take care
Mike

Not as yet - can’t find the plug anywhere! Can’t see it from inside the van and from rear it looks like it goes under the fridge to somewhere but all that’s under the fridge from inside the van is the setec III - no plug/PowerPoint that I can see.