haunted fridge

[GKLarson]

My Dometic fridge (model rm2652) runs fine on AC but propane operation has been acting up. Ran on gas fine for 6 continous months last winter in SW then quit & would not re-ignite. After running it on AC for day, gas operation again functioned properly but after a 600mile trip it again quit after 7 days of working fine. It was then turned off for a wk & would not restart on gas although it again worked fine on AC
Yesterday I had a handy friend look @ it but naturally it behaved properly & fired right up for him. He suggested cleaning the grounds
I've also read the vent/stack can get clogged & cause problems. Looked @ cover on roof just now & it appears I'll need to remove caulk to get @ screws that mount cover & will want to have a good replacement caulk available before removing cover.
Can any of you handy folks offer any advice for a mechanically challenged guy to try before taking unit to a pro for repair ?
Also what's good caulk to use to re-seal cover mount screws or anywhere else on roof ?
Thanx much for any help

[JohnB]

Does the unit start to go click click click click when you fire it up on LP? Need to know if you are at least getting the ignition sequence to work.

Cleaning the grounds is a for sure a sound thing to do but it comes back to the click click click. If you have no spark or not good spark that is problem 1. If you have the ignition and good ignition but no flame that then points you to a different mission of search and destroy... No gas, clogged vent etc.

You need a good strong click, click, click. Not a 1 fire then nothing then a 2 fire then nothing. If everything is working right the igniter will keep firing one right after the other until it time outs, stops clears the gas, then try’s again for a time period, then stops. Lets the gas clear then try’ s again. After 3 attempts it goes out on safety and the trouble light inside comes on and will not try again until reset.

We have to start with, does the ignition work “right” and then does the burner light? Tell us some more to help point you where to look for next

For the vent stack, you use Dicor self leveling lap seal caulk to fill those screw heads back up.

What year is your camper so I know what vintage you have?

[GKLarson]

JohnB
Thanx for the reply
I much apprecate you're putting your analytical mind to work on my fridge issue.
3x now today I've had wife turn on the fridge while I stood outside watching & listening to rear of fridge. I had previously removed the windscreen to have better access & sight of what's going on during startup. Each time today it was only necessary for the igniter to fire once to get the unit working properly
That wasn't case, however while we were away & fridge refused to ignite.
During those failures I could distinctly hear the igniter firing a series of 5 times, then pausing before making a 2nd then 3rd series of 5 more clicks before timing out as you described. While those clicks were happening I held a lit flame in front of the oriface where I'd previously been sucessful in lighting the burner, but it failed to ignite despite many attempts. That led me to assume it might be a gas issue ??? (although other gas using appliances worked fine )
My handy pal also suggested a thermocouple issue ??? He was surprised to find it was copper near business end but appeared to be a shielded wire farther back up the line ???
My Sunline is a T-1950 Solaris Lite manufactured in 3-05 VIN # 1LCxxxxxxxxxx
Until I can get some of caulk you recommended perhaps I'll temporarily use a tarp or ridgid plastic to cover the vent cover after I explore whether it's clogged
Thanx again

Edited to remove VIN

[Jim-Bev-2363]

A hand mirror viewed up the outside stack might tell if there is blockage in the back of the fridge. You should be able to see daylight while looking up. The if no daylight the cover would need to be removed.

While other LP units have plenty of gas you might still have a LP system leak for the fridge burner.

jim

[Gene]

Originally Posted by GKLarson

...During those failures I could distinctly hear the igniter firing a series of 5 times, ...

As JohnB said, that is a good sign

Originally Posted by GKLarson

... While those clicks were happening I held a lit flame in front of the oriface where I'd previously been sucessful in lighting the burner, but it failed to ignite despite many attempts. That led me to assume it might be a gas issue ???

Yes, probably a gas issue. When mine has been off for several months I sometimes have to go through the sequence of trying it 2 or 3 times. Check light comes on, turn fridge button off then on again.

It could also be the gas valve solenoid ... When you first turn it on do you hear a "Clunk" from the gas valve followed by the "tick" "tick" ... from the spark?

Gene

[awellis3]

Originally Posted by Gene

It could also be the gas valve solenoid ... When you first turn it on do you hear a "Clunk" from the gas valve followed by the "tick" "tick" ... from the spark?

Good point. You should hear the valve open. "Clunk" and no gas = blockage. No "clunk" = control module or solenoid.

Teach

[GKLarson]

Thanx for all the helpful replies
It's difficult to determine cause of problem when unit's currently functioning properly
In thinking about issues raised here some things come to mind - On 2 occasions now after operating properly for an extended time (6 months & 8 days) the fridge suddenly quit. Assuming ignition's only needed @ start-up, doesn't that imply a gas issue ?. Also, I definitely hear both the clunk @ initial start up & the series of clicks (although the series is cut short by successful early ignition) But while trying w/o reults to re-light w/ a flame during last malfunction I could hear the repeated series of 5 clicks.
Once recently prior to a successful start up I saw & heard a small gas explosion that produced a very quick flash & small ball of flame ("That's not good", I thought & "glad I didn't have my face any closer !)

More ineptitude on my part - I can't seem to figure out how to get a mirror in position to view up the stack ???. It has a solid bottom beyond where combustion occurs & no other acceess apparent to me unless one needs one of those miniature mirrors dentists use in your mouth ?

Thanx again for all the helpful replies. This Klutz appreciates it. I' tried to give back a little to the forum on a thread re car-topping a boat, a subject more familiar to me

[Gene]

Don't think of yourself as inept or a klutz, just someone searching for answers and information. That is what this forum is for, to help each other with things that are new to us. Goodness knows, I have learned a lot here from those that have "been there, done that".

Troubles like this that come and go are not easy, particularly for the one have the problem. You WILL get it fixed .... even if we have to call Ghost Busters.

Gene

[Jim-Bev-2363]

Originally Posted by GKLarson

Once recently prior to a successful start up I saw & heard a small gas explosion that produced a very quick flash & small ball of flame ("That's not good", I thought & "glad I didn't have my face any closer !)

Maybe you could try to tighten the fitting on the copper supply line. Maybe all gas line fittings wouldn't hurt.

jim

[JohnB]

Originally Posted by GKLarson

In thinking about issues raised here some things come to mind - On 2 occasions now after operating properly for an extended time (6 months & 8 days) the fridge suddenly quit. Assuming ignition's only needed @ start-up, doesn't that imply a gas issue ?. Also, I definitely hear both the clunk @ initial start up & the series of clicks (although the series is cut short by successful early ignition) But while trying w/o reults to re-light w/ a flame during last malfunction I could hear the repeated series of 5 clicks.
Once recently prior to a successful start up I saw & heard a small gas explosion that produced a very quick flash & small ball of flame ("That's not good", I thought & "glad I didn't have my face any closer !)

Hi GK,

You have told us a lot, good info. This above and your prior post rules out a number of things.

The good news is, it is now working. But what was up?

Your model/year is only 1 year newer then mine. May only be a several months pending what month it was installed.

Here are some things to think and look for if things start acting up again.

Since you have 5 good clicks in a row, that is a good start. Means the control board is working to the point it senses you need cooling and sends a signal to the gas valve and igniter. The 5 good clicks in a row and not skipping may be OK or not. Read on for the duration of how long the clicking is going on for.

However having good clicks is only part of the need. The spark has to jump the gap at the burner in order to ignite the gas. The electrode "might" be something to investigate. If the insulator is cracked or the gap too big then while you hear clicks that does not always mean the spark is snapping where the gap is. When you said you heard a "poof" that points to having too much gas and then spark ended up in it and went "poof" but maybe not sparking in the right location. Checking the gap and the insulator is a prudent step. See here





Then there is the igniter cable, if you hear a snap do you see a spark at the burner? If yes then sparking is good and in the right place. The igniter can snap but a skinned or broken cable or cracked insulator will make it jump the gap some where else then at the burner.

The gas valve and the igniter run off the same signal and stem from the same wire out of the control board. So if you have clicks then power is going to the gas valve. Do not know if the gas valve is opening but both are on the same signal. If you hear the clunk of the valve then odds are more in favor the valve is open. May be a plugged jet but open valve.

At the end of the gas valve is a brass orfice with a real small hole in it. The gas flows through that hole and into the burner tube. Make sure no dirt is in the area and be carefull to not accidentally jam dirt in the orfice trying to clean it out. The orfice has a man made ruby in it with a spiral pattern and you should not blow compressed air towards it or poke anything in it as that can affect the precision orfice. Dometic recommends soaking the nozzle in alcohol based solvent for an hour to clean it. Remove the nozzle and soak.

The igniter has a feed back circuit that once the flame lights it changes the resistance in the igniter cable and stops the sparking. The igniter is still powered but no spark will come until the flame stops and it starts back up again. This is why the sparking stops as soon as the flame is present.

The thermocouple is the safety part. It is looking for heat to send a signal back to the control board that flame is present after trail-for-ignition is successful or not. If after many many seconds no flame shows up then it shuts down the fridge on safety. This thremocouple is not like a capiliary tube in a pilot operated gas valve holding the valve open, it just sends a signal to the pc board that flame is present. The PC board then figures out to shut the gas off or not.

There is one thing that does not sound right and I have to dig more to confirm. You said you only heard 5 clicks and then it stops. H'mm I do not recall on the Dometic fridge a 5 click cycle. Trial-for-ignition I thought was a 45 second period. See this except from Domectic.

Gas Mode
Note: All current Dometic control boards are 3 try systems in the gas mode. There is a 2 minute purge cycle between each trial for ignition. Flame failure will take 6 to 7 minutes.

It is a 3 try system with a 2 minute purge in between try's but I thought the Trial-for-ignition period was 45 seconds which is more then 5 clicks. Let me dig some more on that time length. If I have the 45 seconds right it should keep trying that long. If you hadt any kind of flame the igniter would stop quick and restart instantly when the flame drops out. So it leaves a question did you have intermittent flame creating a 5 click, had some flame, flame went out and then sparking starts back up verses just burning like it is suppose to?

Hopefully these thoughts might "spark" (a joke there...LOL) some thoughts on things you remember. You are giving us great detail to go on. Armed with some of the above if it acts up look for what is going on in what order.

Hope this helps

John

PS I edited out your VIN above. I was only after what year the unit was to know if it has the newer systems on it.

PS2. We too are learning from your great observations. So you are helping all of us by reporting back. You are just a fellow camping bud looking for some help and we try the best we can. Thanks!

PS3. Tell us more about you where lighting the gas by hand, I read that to be a bic lighter or grill lighter. Did the igniter stop sparking when the lighter flame reached the electrode? And it might start sparking again if the flame went out or you pulled the lighter back. I too once had to light the unit by hand after a long drawn out saga of forgetting to turn the gas on. It was like the igniter got weak sparking so much and it started and stopped sparking. Once past that saga it has fires off in about 2 clicks every time. But I did buy a spare igniter coil just in case. Boondocking and having the fridge go out is a big deal. So I have a full supply of parts now.

[JohnB]

To add this this thread, today I double checked out our fridge today on LP. We are heading out next week for boondocking adventures and did the yearly clean up and check.

Since the LP line was full of air not being run on gas in a while I counted the number of clicks in a row. But the time I went out side quick from turning it on, it fired 22 times in a row before it fired off purging the line out. It had to of fired a few times before I could of made it out there. It created spark about 1 spark/snap per second. I looked and I can seen even in sunlight the spark jump the gap from the igniter tip to the LP burner tube. A nice fine blue spark.

So, the 45 seconds trial-for-ignition seems to fit for a 2004 unit. The igniter should spark non stop in about 1 second intervals until it times out after 45 seconds, then a 2 minute purge, then starts over for 3 try's and then go out on safety. If during the firing sequence the flame actually starts the heat will be sensed and shut down the sparking. As soon as you loose flame it will immediately start sparking again if the control is calling for cooling.

So, the 5 seconds sparking that was talked about then stopped then started again is either a weak igniter or it actually lit the burner and it went out quick and started sparking again. If you have the small access cover off you can see this sparking action.

Under normal LP operation once the unit is purge of air and up and running, it only takes 1 or 2 snaps and the burner is lit. An igniter that is weak and cannot hold a constant firing sequence may not rear it's ugly head until the gas is not working right or you are air bound.

Hope this helps

John

[GKLarson]

After again operating properly for a time , our fridge again refused to work on gas the day before a planned departure. A local RV dealor agreed to look @ it that afternoon & was 99% sure it was a faulty electrode.
In 15 min he had a new one installed & fridge fired right up on 1st spark.
He didn't charge extra for me to watch so if these normally wear out over time I may be able to effect next replacement myself ?
Perhaps it would be wise to carry along a spare ?
Thanx again for all the help received here

[JohnB]

Hi GK

Thanks for reporting back. Good to know.

The unknown is did the electrode tip wear out or did the insulator crack sparking some where else?

I have not seen enough of them to ever see one wear out. I'm sure in time they might.

They are not hard to install, have to watch the gap is right and set it if needed and do not flex the insulator much or it will crack.

After my run in with the fridge not lighting it dawned on me on just how important to a boondocking setup the fridge is. When you are buried in the woods, a fridge chucked full of food and the fridge dies, that is a problem. The AC can stop, the furnace can stop, the HW heater can stop even the water pump. Those create a large inconvenience but not like a fridge that goes out.

I know I may be the exception but I now have an electrical part for everything in the back side of the fridge except the inside top control board. If it goes out I can hot wire the control board to limp until I get one. So if your camped next to me, I got ya covered....

I'm not saying run out and get a full set of spare parts but understanding how the thing works and what tweaks you can do does help get you up and going some times. If your not into the techno trouble shooting, an empty ice chest that you can at least put ice and food in is a backup and a lot cheaper then a set of spares.

Thanks

John