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Topic: Fridge RM 3662 issue in gas mode.. (Read 528 times) previous topic - next topic
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Fridge RM 3662 issue in gas mode..
I initially forgot to purge the gas and it failed to light.  I have now purged and re-purged with the burners. The fridge lights and after 30 seconds the flame goes out and the "check" light illuminates.

We drive from Southern California to Toronto, arriving two weeks ago, without any fridge issues.

Any ideas?
1999 26.5 Rear Bath
Re: Fridge RM 3662 issue in gas mode..
Reply #1 –
Sounds like the thermocouple is faulty. The thermocouple senses the flame and will keep the propane flowing by sending a small voltage to the controller. If the flame were to be blown out the thermocouple no longer generates that small voltage thus  telling the controller to shut off the propane so you don't blow yourself up in the event of  a stray spark  while unburnt propane is pooling in your rv.

Steve
2003TK
Re: Fridge RM 3662 issue in gas mode..
Reply #2 –
Including the year and model in your signature is helpful to us when discussing your rig's problems.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fridge RM 3662 issue in gas mode..
Reply #3 –
Have you cleaned your burner tube?  This is a must on your maintenance schedule......lots of YouTube videos showing how it's done....very easy........

Bill
2013 31' Silver Twin Bed
Semi-retired 6/21....
Re: Fridge RM 3662 issue in gas mode..
Reply #4 –
Thanks for the advice.  Will give these a try
1999 26.5 Rear Bath
Re: Fridge RM 3662 issue in gas mode..
Reply #5 –

Should you decide to change out the thermocouple the part number is 2932052018. You can find these on Amazon for  as low as $22. This is the one I ordered and is working great so far:

Amazon.com: MC Enterprises 2932052018 Thermocouple: Automotive

As an Amazon Associate Lazy Daze Owners' Group earns from qualifying purchases.
Steve
2003TK
Re: Fridge RM 3662 issue in gas mode..
Reply #6 –
Quote from: 73gitane  - 
Should you decide to change out the thermocouple the part number is 2932052018. You can find these on Amazon for  as low as $22. This is the one I ordered and is working great so far:Amazon.com: MC Enterprises 2932052018 Thermocouple: Automotive

A 21 year-old refrigerator can have a wide variety of potential issues that can cause starting or running problems.
Thermocouples can be checked with a voltmeter that measures millivolts and is a regular test, suggested by Dometic in their service manuals. Dometic specifies that, when hot, the thermocouple should produce 25 to 35 millivolts.
Lower voltage readings can cause erratic or no gas operation.

The troubleshooter in me prefers verification that a part is defectivet before replacing it, if possible. I feel stupid when replacing a part that I suspect is bad, but have not confirmed, and it is was good. Not a best practice for a mechanic and it's hard on the pocketbook.

Larry
As an Amazon Associate Lazy Daze Owners' Group earns from qualifying purchases.
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
 
Re: Fridge RM 3662 issue in gas mode..
Reply #7 –
If your frig has electronic ignition and lights for 30 seconds then goes out I would clean the flame sensor. I haven't really looked ours so I cant tell you what it looks like. It should be a little rod positioned in the burner flame with a wire going to the main board. This is true on a furnace and I bet these are simulare. I clean them with a little piece of sand paper, Very gently because gap is critical.

Jon
1994 MB
Re: Fridge RM 3662 issue in gas mode..
Reply #8 –
Quote from: JonS  - 
If your frig has electronic ignition and lights for 30 seconds then goes out I would clean the flame sensor. I haven't really looked ours so I cant tell you what it looks like. It should be a little rod positioned in the burner flame with a wire going to the main board. This is true on a furnace and I bet these are simulare. I clean them with a little piece of sand paper, Very gently because gap is critical.

Jon
I have found that a soft bristle toothbrush works great...this assumes you use it as part of your regular maintenance.....

Bill
2013 31' Silver Twin Bed
Semi-retired 6/21....
Re: Fridge RM 3662 issue in gas mode..
Reply #9 –
Quote from: Larry W  - 
Dometic specifies that, when hot, the thermocouple should produce 25 to 35 millivolts.
Lower voltage readings can cause erratic or no gas operation.

Larry

The thermocouple hits 24 millivolts before it goes out ~30 seconds into burning, so it's not quite getting to that 25-35 mV range but ohhh so close.

I gave the thermocouple a light sandpaper, cleaned the contact points on the motherboard, and cleaned out the burner.

It's very humid in this area right now, and we came from zero humidity.  Wondering if that could be contributing to the issue.

Next I will try plugging it in to make sure the issue isn't only in gas mode (ordered a 30A extension cord so that it can reach an outlet where we are staying, and it just arrived).


If it's cold when I wake up, I'll order a new thermocouple, as I am out of ideas.

Thanks for all of the help!

Brad
1999 26.5 Rear Bath
Re: Fridge RM 3662 issue in gas mode..
Reply #10 –
Has the refrigerator's gas jet ever been cleaned?  The jet's small opening can build up deposits that reduces the flow of gas and the size of the flame.
Too low a flame could prevent the thermocouple from reaching it's normal operating temperature quickly, it can also reduce the cooling capacity of the refrigerator.
The jet can be removed and for cleaning. Soak in alcohol or other solvent and then brush clean with an old toothbrush, never poke anything through the jet, especially metal, doing this can change the shape of the jet with poor results.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fridge RM 3662 issue in gas mode..
Reply #11 –
Cleaned the jet this morning and hit 25.6 millivolts before it shuts down.

Fridge is working fine in AC mode.

I called an RV shop this morning to price a new thermocouple, and they don't think that is the issue.   Their thought is that it could be a magnetic valve in the gas line.  From what I understand, the thermocouple sends a current to this valve which is what keeps it open.  They recommended that I do not work on the gas line, which seems reasonable, and said they will diagnose it for free.

Will update this thread with the outcome.
1999 26.5 Rear Bath
Re: Fridge RM 3662 issue in gas mode..
Reply #12 –
Quote from: b_mobile_bradley  - 
Cleaned the jet this morning and hit 25.6 millivolts before it shuts down.
I called an RV shop this morning to price a new thermocouple, and they don't think that is the issue.  Their thought is that it could be a magnetic valve in the gas line.  From what I understand, the thermocouple sends a current to this valve which is what keeps it open.  They recommended that I do not work on the gas line, which seems reasonable, and said they will diagnose it for free.

Is your LD's refrigerator the original? If so, I wouldn't spend too much for repairs on a 21-year-old unit.
Few make it to this age before the tubing rusts through and the liquid contents leak out.
The control board could also be failing.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Fridge RM 3662 issue in gas mode..
Reply #13 –
Quote from: b_mobile_bradley  - 
Cleaned the jet this morning and hit 25.6 millivolts before it shuts down.

Fridge is working fine in AC mode.

I called an RV shop this morning to price a new thermocouple, and they don't think that is the issue.  Their thought is that it could be a magnetic valve in the gas line.  From what I understand, the thermocouple sends a current to this valve which is what keeps it open.  They recommended that I do not work on the gas line, which seems reasonable, and said they will diagnose it for free.

Will update this thread with the outcome.
Bradley, thanks for keeping readers updated on your refrigerator troubleshooting. It's valuable information for those who may have similar problems down the road.

Chris
Formerly: 2002 30' IB
Re: Fridge RM 3662 issue in gas mode..
Reply #14 –
Quote from: Larry W  - 
Is your LD's refrigerator the original? If so, I wouldn't spend too much for repairs on a 21-year-old unit.
Few make it to this age before the tubing rusts through and the liquid contents leak out.
The control board could also be failing.

Larry

Thanks, Larry.  I'll price a new fridge as well.
1999 26.5 Rear Bath
Re: Fridge RM 3662 issue in gas mode..
Reply #15 –
Good news, it ended up just being the thermocouple.  I've got a good story to go along with it..

As you know, the place that I had called convinced me that it was something wrong with the gas line and it would be dangerous and illegal to attempt to repair on my own.  So I took it in.  The mechanic was a different person than I had talked to on the phone.  He insisted the issue was with the main board.  He refused to try changing thermocouple, even though I already had the heat shields off and it would only take a few minutes.
So the mechanic proceeded with the main board, removing mine and installing a new one.  It seemed to work initially and that's when he informed me the part is $300 (I'm in Canada at the moment).  I nearly choked, but my partner and I agreed that we needed the fridge running properly so we were ready to bite the bullet.  And then the same thing happened, there was a click and the flame went out. At this point we're about 20 minutes in.
He fiddled with the board and all of the wires for another 10 minutes, thinking there was a loose wire somewhere.  He kept restarting the fridge, but the gas kept kicking off.
Beaten, the man then says "well I guess I'll try the thermocouple, but that won't be it"..  He didn't have a new one, but he had a used one he had pulled off a fridge that he swapped out at some point in the last 20 years.. It literally took him less than 3 minutes to remove mine and install it, and guess what - it worked!  The fridge kept running.
Now we've got a $30 used thermocouple and a $300 new board in the RV, and he asks if I want to keep the board.  HAHA.  No thank you, please put mine back in.
Well it turns out, mine is slightly different than the new ones that he's accustomed to installing and he can't remember where the wires go.  I watched him try to figure it out for what seemed like ages.  I knew where the thermocouple wires go, because I spent so much time trying to fix it.  But he wouldn't listen to me and kept disappearing to look for manuals I presume.  I should add that the weather was about 90F and 80% humidity with full sun.  It was unbearable.
Finally he gets my board back in and everything works fine.  I was quite frustrated at this point, but keeping my composure.  I told him that the only reason that I happened upon his shop is because I was pricing a new thermocouple but was convinced to come in to diagnose the gas line.
I wait around another 10 minutes for the admin person to come out with the bill... and then she hands it to me... $165!!!!!!!!!
I couldn't believe it.  I asked for an explanation and was told the part is $30 and the rest is labour, 75 minutes of his time.  I really tried to keep my cool and discuss the sequence of events that led to such a large bill, but they weren't having it.  That was the cost.
At this point I've been at this place for about 1.5 hours in the sweltering heat and my patience is out.  I refused to pay.  I said they could take their used thermocouple out of my RV, but I'm not paying because all of the errors were on their end.
Another employee came out to argue, so we had 3 people telling us we had to pay the $165.  I flat out refused and said I was going to take out their thermocouple myself and leave.
The mechanic who did the work cussed us out and then told the admin person to only charge me for the part.  He went into the back and I didn't see him again.  I felt bad for the guy because there was clearly broken communication between the person answering the phone and the mechanics, but I wasn't about to pay for their mistakes.  That and he changed out the most expensive part before trying what I wanted.
So now I have a used thermocouple.  Who knows how old it is and how long it will last, but our fridge is working.  I think I'll order new one to have as a spare.
It really felt like I was getting scammed, but I think it was just a case of bad company procedures and a stubborn old mechanic.
1999 26.5 Rear Bath
Re: Fridge RM 3662 issue in gas mode..
Reply #16 –
Well, I was a maintenance technician for 50 years or so, (still am but not so intense), and usually I try the simple, quick and easy stuff first. Diagnostic equipment is a big plus. Digital cameras are a great tool when lots of undocumented wiring is present. I used to make a drawing of wiring before I touched anything.  I would have paid for at least some of his time. But not the time it took him to take out your board, and then put yours back in.  If they had a board, they should have had a new thermocouple. 
    It seemed likely that the gas plumbing was ok, except possibly the electric gas valve. I'm glad they didn't just 'rip' into that first.   RonB
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB