TheSamba.com :: View topic - Dometic Fridge

Wed Aug 08, 2018 1:16 pm

Tried again this morning. Same old nonsense. I was able to get it started, but only after running on AC/Shore power for 1/2 hour or so. No real rhyme or reason to the order of operations.

I keep getting the fast blinking light which, as the video below shows, seems related to a low-gas condition. Just wondering why I would be getting that after turning on the tank valve and the valve in the fridge and lighting the stove. Why would that abate after letting the fridge run on AC for a while? (Not positive of a cause/effect here, but that's what seems to be happening).

Wed Aug 08, 2018 2:01 pm

It's not unusual to have to run it on 110 or 12 Volts for a little while to get it to start. The preheating of the 12V or 110 heat element causes the air to begin rising in the exhaust which pulls in fresh air. Lack of fresh air is what normally keeps it from starting. Some people pump the air thing or some have put a bicycle pump on the drain port to play around with it. But in practice, I put mine on 12V as I am getting ready to leave on a trip and I don't switch it to LP until I get to camp and it always lights. If I want to run it on LP to precool it, usually just several minutes is enough to get the heat element warm so it draws in fresh air. If you want to experiment without precooling anything, try pumping the plunger to bring in some fresh air in while it tries to light. That might work but you might have to keep pumping air for a bit to keep it lit.

I can't see how the sparking module knows whether it is getting gas or not. But maybe I am missing something. Anyway, I would not get confused about it, if it is fashing it is not lit and if it stops flashing it is lit.

On your thermostat dial, it makes almost no difference where you set it. It has 2 levels, pilot light and flame. The flame doesn't get bigger the more you tune the dial. [On 12 Volts it only has one level and it ignores the thermostat all together]. A warm fridge is always going to be on flame regardless of the position of that dial. Once it has cooled down some, if you turn the dial way down, you will hear it click at the set point and it will go into pilot light mode.

It also does nothing to put it on max. That will only make it get colder at night because it is running flat out during the day in hot weather. I leave mine at about 8 o'clock on the dial otherwise things will start to freeze overnight when our temps drop a lot at night here in CO. But during the day turning it to max doesn't do anything because it never reaches its set point even if it is set to 7 or 8 o'clock on the dial. Basically 8 o'clock on the dial equates to about a 32 degree interior temperature which it never gets to during the day.

Wed Aug 08, 2018 3:40 pm

Is there any reason why you are holding down the flame button on the far right? Not seeing that in any instructions. (I tried it anyway).

Still experimenting but may wind up taking out fridge for full inspection.

Thanks.

Wed Aug 08, 2018 3:50 pm

The internal tabs that hold it down broke when I was trying to clean it. That's how I ended up with a manual sparker; I thought the electronic sparker wouldn't work at all if it didn't stay down, but you can hold it down to spark and once it is lit, the button doesn't have to stay pushed in (except it won't start sparking again if it blows out). So I didn't really need the manual sparker after all but now that is is there, I like having it as a backup.

Wed Aug 08, 2018 6:58 pm

Ahhh. Gotcha.

I'm taking this fridge out next chance I get to see what's what. I actually do like it when it works. Based on what I've read, I'm thinking the electrode and vents need cleaning. Couldn't hurt, anyway. I may also replace the igniter if, after the cleaning, it stays solid orange like it did again tonight. Might be this ridiculous NJ humidity but who knows.

Thu Aug 09, 2018 8:44 am

You also have bad aux batteries per your other thread, so have you tried seeing if you get the same sold red light when the van is running and providing higher voltage?

Cleaning the burner box is a good idea if you take it out. I'd leave the thermocouple (electrode) alone. They never go bad and you may break the tip off. The high heat keeps them clean. But blowing out the burner box and squirting alcohol through the gas jet is a good idea. Try not to destroy the burner box seal but if it gets broken, you can use a little bit of high temp sealer instead, it is just harder to open up the burner box the next time. Also try not to flex the exhaust and intake hoses when you take out the fridge as you can create a new problem if you bend them too much. You have to tip the fridge backwards as it comes forward to the exhaust vent clears the cabinet and when you first pull it forward it helps to have someone outside looking to make sure the exhaust flange isn't hanging up on anything. It is simple if you are careful, just saying.

If low voltage batteries isn't causing the steady read light, then I personally would just replace that electronic unit while you have it out. That link I shared, they only cost $30 and will save you having to take the fridge out again. It is a weak point and the most likely suspect anyway.

Thu Aug 09, 2018 9:03 am

I was able to get it started this morning after running on AC again.

If I can establish a predictable procedure, I may forego taking it out. The igniter is working. The only time I don't get a spark is when the refrigerator has been running on DC for a while. I can only leave it on for about 20 minutes before lighting it on propane. Any longer than that and I get a solid red light, no ignition.

I will study the removal procedure closely and take your advice if I go that route. This sounds more like a winter job to me as I'm using the van just about every weekend and enjoying the hell out of it before the cold weather sets in.

Dave, you are a tremendous resource. Thanks.

Fri Sep 07, 2018 8:47 am

Yesterday, I was fooling around with the westy and decided to fire up the dometic via propane in mid 70's weather. The red light would not blink. Finally gave up and decided to do it with the highly suggested method of first using AC fireup, then switch over to propane. After a couple hours of AC usage, I switched over to propane and it fired right up.

Fri Sep 07, 2018 9:33 am

cmayna wrote: Yesterday, I was fooling around with the westy and decided to fire up the dometic via propane in mid 70's weather. The red light would not blink. Finally gave up and decided to do it with the highly suggested method of first using AC fireup, then switch over to propane. After a couple hours of AC usage, I switched over to propane and it fired right up.

I often have issues like this. Sometimes if I press the igniter button, the light goes solid red and the refrigerator cannot be lit. Other times, the light will not come on at all, same result. 100% of the time, if I press the button for the igniter and let it sit, I'll start hearing clicking within 20-30 minutes, at which point I can get it to light. Probably some problem with the igniter that needs repair - but low on the list since it always does end up working after some time.

Fri Sep 07, 2018 10:21 am

Hi,

Clean spark electrode in combusiton chamber, check electrical connections on the ignitor. Test. If still not satisfactory, I'd change the ignitor.

Sun Sep 09, 2018 7:04 am

On my 91, I'm able to get the fridge working on propane but without the ignitor/flame button on the far right staying depressed.

In other words, I have to stop the clicking and then I see my flame light grow brighter. In the past, the igniter button would stay depressed. However if I keep it depressed now, the flame light never grows. I guess I'm just concerned that if the flame goes out it will not go into reignite mode and gas may build up.

Does that ignitor button need to stay depressed for safe operation?

Sun Sep 09, 2018 10:12 am

No the igniter button does not need to stay depressed for safe operation. There is a thermocouple in the combustion chamber that is always in contact with the flame. This keeps a gas valve open that will otherwise close if the the thermocouple senses a loss of heat, ie. the flame blew out. It takes a few seconds for the thermocouple to cool and the valve to close and cut off the gas so if your igniter button is depressed and your igniter is not 30 years old (simple fix to a lot of the issues on this thread, clean combustion chamber and install a brand new igniter) the flame will re ignite before the thermocouple cools and the fridge will reignite before you even know it has gone out. This is one of the big advantages to the electronic igniter on the 1991’s over the piezo manually activated igniter on the earlier models.

The thermocouple is the reason that you have to push and hold the button on the mid/left of the control panel when you start the fridge because you are physically holding the thermocouple controlled gas valve open until it senses a flame and stays open as a result.

Sun Sep 09, 2018 5:11 pm

Thank you! Used it all day today and it worked like a charm.

Sun Dec 09, 2018 8:42 am

A little video I did about the Dometic unit.

Cheers!

Sun Dec 09, 2018 11:13 am

I remember watching this video as part of my troubleshooting. Very informative and fun !

You don't look much like your avatar picture though... :P

Tue Dec 11, 2018 12:22 pm

Great video! The answer to his wonder about why precooling the fridge on AC makes the fridge easier to light on propane is that the AC heating element in the chimney creates a light air flow up the chiminey which encourages a good air propane mixture for ignition. Without this flow it is up to the operator to get the mixture correct and that’s why some people are good at it and some hate it. Same thing applies if you run it on DC for a short time before lighting on propane.

Sun Oct 25, 2020 1:51 pm

Hey Brain Trust Guys!

Thought I would add to this nice related thread rather than start a new one.

'New-to-me' 1990 'new style' fridge (and thrilled to have it!) - BUT someone has stripped every single thing required for the propane operation. The auto igniter and all related wiring is missing, as is the red square light above the three large push buttons (making the title of this thread even more appropriate - I also have 'no red light' - quite literally! :) )

The sparker is also missing.

My questions are:

1) Is the 'newer' style auto-igniting fridge worth the effort and $ to save? Or is it simpler just to go to with say the '87 style with manual igniter and not worry about repairing this one? Is the red square light (and sparker) things that can even still be purchased? I see replacement auto igniters are available.

2) Before I hunt through a million wiring diagrams, does anyone know off the top of their head where the black wire from the spade terminal on the side of the 'Safety Valve Button' (red arrows in the pic below) connects to? Is it just a ground? That wire is missing on mine as well.

Sorry, totally new to these fridges! Really appreciate any input on this - enamored with the 90/91 style but have an older one readily available if that's the more practical option.

Sun Oct 25, 2020 2:18 pm

In the photo, the wire to the igniter is missing because you probably have the new style Dometic with the auto igniter - sweet. (The shaft at the end of the push-in air pump triggers the igniter.) Not sure where you could find a new, replacement igniter. Maybe one of the shops that service the big RV's.

Yes, typical replacement Auto-igniters are available. A great upgrade for the older fridges BTW. About $50 as I recall.

Sun Oct 25, 2020 4:31 pm

Hi John,

Thanks for the info! I do indeed have the new-style fridge, and there apparently is no manual igniter setup from factory behind the push-in air pump on the 90/91 - the case has never been drilled for the mounting screws for one. The wire I'm wondering about actually goes to what's labelled as the 'Safety Valve Button' in the literature.

Is the 'sparker' (mounted at the very bottom back of the fridge, in my first pic) identical to the early fridges? I would think it likely is, in which case I'm sure I can find one and it would only be the availability of the little square red light keeping me from getting this thing running again. Only so many people parting out 90/91 fridges, I would think.

Sun Oct 25, 2020 9:50 pm

I've read of people installing auto-igniters on older fridges, so i fyou have a functional "87 fridge, that might be worth considering. Do a search on the forum.
I have a '90 as well, and indeed there is no igniter at the manual pump. Auto-igniter only. So someone on this forum actually added a manual igniter to their '90 fridge! That way when the autoignitier goes bad, you have a backup.

The autoigniters are easily available at the usual Vanagon vendors, and also at all the RV places.

As for the LED, I imagine you could plug in any off-the-shelf LED and go with it. Good luck!