Dometic/Electrolux RM 6401L Fridge

[Ggohd]

Hello,
I have the above fridge in my 2001 motorhome, so assume that it is about 15yrs old.
Fridge works well on 230, 12 and gas.
BUT. While lighting the gas is no problem, getting it to stay lit on releasing the button is.
So I have assumed that the signal telling the control box that the flame is lit is not getting through. (sometimes)
I have just changed the thermocouple and it does not seem to have made a significant difference. Sometimes it lights and stays lit without a problem, other times it will only stays lit after the knob has been kept pressed in for some time, like 5 minutes.
I have ensured that the thermocouple is well in the flame, which is a healthy blue colour. I have blown out all the tubes and around the burner with high pressure air.
As this is an inconsistent problem it has caused much head scratching. Perhaps the control box into which the thermocouple is intermittently faulty, has anyone heard of this.
Anyone knowledgeable about these things?
Thanks in advance.

 

[Canalsman]

A common problem with these fridges is solved very simply ...

The control knob does not go in far enough when pressed, sometimes fouling on the fridge fascia.

Remove the knob and depress the shaft whilst lighting. If this works, try pushing something into the back of the knob so it sits slightly further out.

 

[Lee]

You need to check the 'wire' connected to the back of the on off button, it's not a wire it's a tube with a wire inside which is connected to the flame failure device, if this is kinked or squashed it will stop the device from working properly.

 

[Ggohd]

A common problem with these fridges is solved very simply ...

The control knob does not go in far enough when pressed, sometimes fouling on the fridge fascia.

Remove the knob and depress the shaft whilst lighting. If this works, try pushing something into the back of the knob so it sits slightly further out.

The control knob has two functions. There is a centre thin core which seems to operate the safety bypass so the flame can light. Then there is a rotary shaft which does not go in, but controls the thermostat on 230v and gas but not on 12v.
As the flame always lights OK I think that the inner thin core is working and operating the bypass. It's when this is released that the flame goes out and the igniter restarts.

 

[Ggohd]

You need to check the 'wire' connected to the back of the on off button, it's not a wire it's a tube with a wire inside which is connected to the flame failure device, if this is kinked or squashed it will stop the device from working properly.

The thermocouple is brand new so it's not that. There is a thinish "wire" partly coiled, silver in colour, which goes into the control box behind the ignition/thermostat knob. I can't see where the other end goes but presumed it was for the cold temperature sensor for the thermostat.

 

[Canalsman]

The control knob has two functions. There is a centre thin core which seems to operate the safety bypass so the flame can light. Then there is a rotary shaft which does not go in, but controls the thermostat on 230v and gas but not on 12v.
As the flame always lights OK I think that the inner thin core is working and operating the bypass. It's when this is released that the flame goes out and the igniter restarts.

The instructions say that the right hand rotary control knob must be depressed for 10-15 seconds after lighting. If the knob doesn't go in far enough, the thermocouple won't latch ...

 

[Ggohd]

The instructions say that the right hand rotary control knob must be depressed for 10-15 seconds after lighting. If the knob doesn't go in far enough, the thermocouple won't latch ...

Got that now, the inner core operates a latching mechanism, I will have a play around with that. Thanks for the explanation. HopefullY!! The actual control box is quite expensive if that needs to be replaced. The gas valve magneto might be a possibility, but I don't know how to test this.
Thanks, I'll report any progress.

 

[ChrisInNotts]

The other thing to bear in mind is that a partial blockage in the jet can cause the flame to be deflected away from the thermocouple. Might be worth trying a new jet as compressed air doesn't always work?

Keith

 

[n brown]

thermocouple - tc
the only way to check if a tc and the valve are working is as follows
undo the small nut on the end of the tc at the box . this goes into a bigger nut, undo this and remove the valve inside. this just slides out and is a cylinder with a spring loaded plastic disc on one end . next bit takes 3 hands ! push the end of the tc against the end of the solenoid , hold in the spring valve and place the other end of the tc in a flame
after a few seconds, enough power should be generated by the heat to hold back the spring valve ,so when you let go ,it's held by the solenoid. when you remove the tc from the flame the valve should release almost instantly
i have had many failed tcs and one failed solenoid ,so either could be knacked,even a new tc

 

[Ggohd]

thermocouple - tc
the only way to check if a tc and the valve are working is as follows
undo the small nut on the end of the tc at the box . this goes into a bigger nut, undo this and remove the valve inside. this just slides out and is a cylinder with a spring loaded plastic disc on one end . next bit takes 3 hands ! push the end of the tc against the end of the solenoid , hold in the spring valve and place the other end of the tc in a flame
after a few seconds, enough power should be generated by the heat to hold back the spring valve ,so when you let go ,it's held by the solenoid. when you remove the tc from the flame the valve should release almost instantly
i have had many failed tcs and one failed solenoid ,so either could be knacked,even a new tc

Thanks for this. It is still working and the flame remaining lit. But, now the flashing amber ignition light has quit. The igniter can be heard by pressing the ear to the fridge and the light up can also be heard. Holding the control knob in for about two minutes sometimes results in success and the flame keeps burning. Just a matter of luck, certainly not reliable. Looks like it will all have to come to bits again. As I have a trip planned for next week I am just going to have to labour away with it until I get a gap long enough to allow the ordering and fitting of parts if needed. Have rigged a G clamp to keep the control knob pressed in, so long as the igniter is serviceable it will re-ignite in the event of flame failure.