Dometic Fridge not working on gas

[Jack TGA]

Hi folks, I have a dometic fridge in a 2010 carado t337. It works fine on hook up. However on gas it is hit and miss and I never know if it's on or not until several hours afterwards when the fridge is cold or not. I can't really see a flame in the internal inspection window, nor outside when I remove the cover. When I turn the selector knob to gas, push the temperature knob in while its set to max and press the igniter switch, I get a whoosh of the primed gas igniting but it doesn't seem to keep burning despite me keeping the the temperature switch pushed in. I've taken the grill off the outside and blown compressed air in the ignition/burner area but it hasn't improved things. I've also tried lighting the gas from outside using a stove lighter and the same thing happens - the primed gas makes a whoosh noise, instantly burns off and then nothing. Any ideas? I've tried it both with only the fridge isolator switch on and with all the isolator switches on. The stove, oven, and heating all work fine.

 

[monzer]

It is sometimes hard to tell if it's lit.

Take a bit of time first to really figure out what's going on.

When you think it's lit are you leaving it on the coldest setting? Try turning it to low or midway setting, a lot of the time these fridges work better set there. Leave it over night with a small cup of water in the freezer to see for sure.

Also worth waiting till dark and looking for the pilot light through the inspection glass. Some times really hard to see in daylight.

I'd try that first and come back after that if not working.

 

[Jack TGA]

It is sometimes hard to tell if it's lit.

Take a bit of time first to really figure out what's going on.

When you think it's lit are you leaving it on the coldest setting? Try turning it to low or midway setting, a lot of the time these fridges work better set there. Leave it over night with a small cup of water in the freezer to see for sure.

Also worth waiting till dark and looking for the pilot light through the inspection glass. Some times really hard to see in daylight.

I'd try that first and come back after that if not working.

Thanks Monzer, but I already know the symptoms: sometimes it works, sometimes it doesn't, even when I follow exactly the same procedure. For example, before writing this post I took the outside grill cover off, so I could really see the burner. It didn't light for 15-20 attempts, then finally lit, without me doing anything different. I'm trying to understand what would make it so inconsistent.

 

[Swifter]

Thanks Monzer, but I already know the symptoms: sometimes it works, sometimes it doesn't, even when I follow exactly the same procedure. For example, before writing this post I took the outside grill cover off, so I could really see the burner. It didn't light for 15-20 attempts, then finally lit, without me doing anything different. I'm trying to understand what would make it so inconsistent.

I had exactly the same problem when I tried to light mine earlier in the year . It think the fridge seems of be the last gas appliance in “ the line “ on my set up . Once lit it was fine but if took forever to get there and did exactly as yours did when trying to ignite it .

 

[xsparks]

Could be the flame sensor probe or the gas selector switch. Contacts on the switch can corrode and cause high resistance.

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[Cush]

If mine doesn’t light you can hear the igniter “ticking’ and when it is lit I can feel warm air coming out the top of the chimney vent outside. I agree that it seems to light best when about 75% flow. Hope this helps

 

[Swifter]

Also worth waiting till dark and looking for the pilot light through the inspection glass. Some times really hard to see in daylight.

I don’t think the OP has a inspection glass to look through on this particular model . Mine hasn’t . That’s why he is removing the vent to see if it’s lit .

 

[xsparks]

If you can reach the exhaust vent check for warmth .

 

[Jack TGA]

Could be the flame sensor probe or the gas selector switch. Contacts on the switch can corrode and cause high resistance.

Are they easy fixes?

 

[Sundowners]

The first time I lit our present fridge---(same style as yours)----I was really struggling------' I removed the outside vent and cleaned the rust from the igniter and sensor ---- also cleaned the burner area out a bit-------I am always wary of damaging these things so carefully does it!!!!
Also check flue is not restricted with rust flakes.
Lights a treat now
As already stated it is much easier to see spark/ flame in the dark!! ---- you can see if spark is where it needs to be!!

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[Jack TGA]

I don’t think the OP has a inspection glass to look through on this particular model . Mine hasn’t . That’s why he is removing the vent to see if it’s lit .

Mine does have an inspection glass but it isn't easy to see if it's lit or not using it.

 

[Jack TGA]

The first time I lit our present fridge---(same style as yours)----I was really struggling------' I removed the outside vent and cleaned the rust from the igniter and sensor ---- also cleaned the burner area out a bit-------I am always wary of damaging these things so carefully does it!!!!
Also check flue is not restricted with rust flakes.
Lights a treat now
As already stated it is much easier to see spark/ flame in the dark!! ---- you can see if spark is where it needs to be!!

I'm assuming the spark is where it is supposed to be because the primed gas always gets lit. What's not happening is the gas staying lit... do you know what could cause that?

 

[xsparks]

Probably need to disconnect gas pipe and pull fridge forward to replace sensor and switch. This tends to vary from one vehicle to another. Suitable components are available on line. You will need fridge details which are to be found inside. Model no etc.

 

[mitzimad]

Possibly jet is blocked and flame to small to be sensed burner full of soot and rust?
Flame is detected by probes the connections for them plug into a box the plugs can be loose or corroded but I would stat with jet

 

[Podney]

Might need a new jet. Is van level?

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[Jack TGA]

Might need a new jet. Is van level?

Fairly, but this has been happening for a month now, in different camp spots.

 

[Jack TGA]

Possibly jet is blocked and flame to small to be sensed burner full of soot and rust?
Flame is detected by probes the connections for them plug into a box the plugs can be loose or corroded but I would stat with jet

What does the jet do? I blasted the whole burner area with compressed air to clean it. Could that not be enough?

 

[Jack TGA]

Probably need to disconnect gas pipe and pull fridge forward to replace sensor and switch. This tends to vary from one vehicle to another. Suitable components are available on line. You will need fridge details which are to be found inside. Model no etc.

What do the sensor and switch do?

 

[xsparks]

The sensor detects flame failure or ignition and the switch selects mains, gas or 12v.

 

[Podney]

What does the jet do? I blasted the whole burner area with compressed air to clean it. Could that not be enough?

Channels the gas to the flame. That was the problem on mine when I had similar problem. Can’t tell you how to clean it as I paid for it to be done when in for other jobs,but I doubt it’s difficult.

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[Swifter]

Mine does have an inspection glass but it isn't easy to see if it's lit or not using it.

Fair play . My mistake , sorry monzer

 

[mitzimad]

Look on you tube for the how to clean the injector or jet you will need. A couple of spanners and a screwdriver
You remove the screw that holds the burner to the flue then pull down to disengage it will the pull out gently towards you
You need one spanner on the square body of the burner and another on the gas connection nuts soon as you have broken the seal it will undo with fingers
The jet is a tiny piece of metal with a very small hole through it it will either stay in the burner or come out on the end of the gas pipe
Blast the pin hole clean with your air duster and shake the pipe to get any debris out
Replace in reverse order and test the nut for gas leaks with soap sudds

 

[Sundowners]

Be careful that you dont lose the jet if you use the compressor to blast it------ better to use aerosol like wd40---- then hold jet to the light ---- it should be a clear round hole. The jet material is soft so dont go poking things through it---- the jet is also very small and easy to drop
With gas flame alight the sensor should be glowing red from the flame------ be VERY carefull if you need to re position it---- it is EXTREMELY brittle------- ( don't ask how I know)

 

[Jack TGA]

Look on you tube for the how to clean the injector or jet you will need. A couple of spanners and a screwdriver
You remove the screw that holds the burner to the flue then pull down to disengage it will the pull out gently towards you
You need one spanner on the square body of the burner and another on the gas connection nuts soon as you have broken the seal it will undo with fingers
The jet is a tiny piece of metal with a very small hole through it it will either stay in the burner or come out on the end of the gas pipe
Blast the pin hole clean with your air duster and shake the pipe to get any debris out
Replace in reverse order and test the nut for gas leaks with soap sudds

Found one thanks!

 

[eurajohn]

If the burner starts OK at first then fails, it will most likely be caused by the thermocouple, possible causes are insufficient flame, poor electrical connection of the thermocouple wiring to the controller, a very common cause where the connector to the controller does not make good contact, the electrical current is very small.
From your description of the problem I doubt it will be flame quality as you say this is an intermittent problem.
The burner assembly is a pre assembled unit with the positions of the igniter and thermocouple probe fixed, it is possible that the thermocouple has moved and is not fully in the flame.
Couple of points, jets do not wear out, if you go down the cleaning of burner assembly, jet etc. when looking through the jet it will always look to the naked eye to be obstructed, don't poke things through it, although quite tough being stainless steel it can be damaged.
If you decide to replace the jet be sure you get the correct one for your fridge, they are not all the same size.

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[Jack TGA]

If the burner starts OK at first then fails, it will most likely be caused by the thermocouple, possible causes are insufficient flame, poor electrical connection of the thermocouple wiring to the controller, a very common cause where the connector to the controller does not make good contact, the electrical current is very small.
From your description of the problem I doubt it will be flame quality as you say this is an intermittent problem.
The burner assembly is a pre assembled unit with the positions of the igniter and thermocouple probe fixed, it is possible that the thermocouple has moved and is not fully in the flame.
Couple of points, jets do not wear out, if you go down the cleaning of burner assembly, jet etc. when looking through the jet it will always look to the naked eye to be obstructed, don't poke things through it, although quite tough being stainless steel it can be damaged.
If you decide to replace the jet be sure you get the correct one for your fridge, they are not all the same size.

"poor electrical connection of the thermocouple wiring to the controller "
What does the controller look like please? (The thermocouple is the bit that sticks into the flame, correct?)

 

[eurajohn]

Looks like this one Amazon product ASIN B00CZRMVNAYes you are correct it does stick into flame, there are actually two, one is the igniter and the other the thermocouple if you follow the wires from the burner they both go to the controller, one of them makes the spark that ignites the gas on start up and the other is the thermocouple that sees that the flame is good and allows the gas to continue to flow.
As long as there is a full and sufficient flame the thermocouple (also sometimes called flame failure protection) will keep the gas valve energised.

 

[mitzimad]

Unless its a very old fridge its a flame rectification probe the box pictured in the last post is where it plugs into those plugs and sockets can corrode and need cleaning

Dirty jets can be intermittent as the dirt drops back when fridge is off