Sunrader Instamatic fridge - attempting recommissioning - help.

[IdahoDoug]

So, I'm messing about with stuff I know little about.  I'm extremely mechanical but am feeling my way along blind with this fridge.  I'm not getting anything on electric - either 110 or 12V so I'll leave those for now.  I turned on the propane, and to my surprise I heard a sound at the back of the fridge and the little needle on the flame meter went to green.  Feeling happy, and wanting to see what was going on outside at the open panel on the outside coach wall, I hopped out to see and was greeted with flames pouring out!  Luckily, I have a Halon extinguisher and good lungs and the latter blew it out.  Some scorched wires that I'll splice - just damage, not melted.  

 

So.  Being the brave/stupid/overconfident sort, I had my wife come get in the coach to repeat the procedure so I could watch what happened, put it out and have some information.  I also videoed it.  The pilot lights (yay).  A few seconds goes by, and then an aluminum block like thing that must be a gas manifold goes whoosh into flames.  I put it out, and here's where I need your help. 

 

Here's the setup, with the first pic showing the pilot light area to the right where the circular hole in the sheetmetal is, then the aluminum block manifold with the main gas line coming into it, and some black relays on it to the center left:

 

Here's a close up of the aluminum block manifold:

 

What I can't figure out is how does the flame front pass from what I assume is only the pilot off to the right by that circular hole in the sheetmetal?  Or does the pilot become the main burner by getting additional gas feed once the pilot's lit, the thermopyle reads the flame is there, and then it turns up the wick?  Or is there another burner set somewhere behind that manifold?  Knowing that would also help me figure this thing out.  

 

So, I got soapy water and could not find any gas leaking from the manifold or any connections.  But my suspicion is whatever is leaking may only be leaking when it's pressurized when the valves are happy the pilot is lit and turn on the main burner function.  So I'm not going to see any leakage unless I can get the manifold into that state.  If that's true, I'm going to have a heck of a time finding what's leaking.  Any suggestions on how to find a leak in that manifold once it's pressurized (without the "flames all over the place" mode)?

Could the burners be plugged and the gas is actually not going into them, but coming back out, revealed when the burner igniter fires off?  I'd be awfully surprised if my search for a leak finds one - I think it's something like the burners are not accepting the gas.. Dunno.  Help.

 

Please no comments that I'm doing something untoward.  I'm 62 and have installed my own gas lines in my house, have messed about with things far more dangerous than this.  There's a little danger in life in all things and I'll get through this with just a modicum of danger. Help me figure out what's going on here from a practical standpoint if you know these old girls.  Thanks in advance.

Edited June 19, 2023 by IdahoDoug

[extech]

there is no main burner. when the pilot lights it heats a thermocouple which allows the gas valve to stay open to keep the "pilot light" lit..  understanding this should help you figure it out

[IdahoDoug]

So what I'm calling (mistakenly)the pilot light (about a half inch high blue flame) out of that cast iron burner is the full extent of the gas usage by the fridge? That's the actual burner?

[extech]

yea  google absorption refrigerator 

[linda s]

That tiny flame is heating ammonia gas in a sealed chamber called the cooling unit. The goal is to just get that gas to circulate, rising on the warm side and cooling on the other side. The change in temp is what cools your fridge 

Linda S 

[IdahoDoug]

Got it.  OK, I've got a gas leak there somewhere, then.  It must be that the burner is properly operating and a leak is producing a cloud of gas. When it reaches the burner - poof it lights.  I used soapy solution and sprayed all over with no luck.  Will try again tomorrow after work.  

 

It seems dead on 110 and also 12V.  Kinda annoying there is no indicator light on the control face to let ya know the unit is on/powered.  You just sit there waiting for the thing to cool and try this and that with no real feedback. Would have been nice to have a light for 12v operation and another for 110 just so you know inside the RV things are working correctly - versus realizing 8 hours later your food is spoiling.

 

I was heartened to find another thread here where a member found the front switches had all corroded just from sitting (British/Irish labels on them) and he found they were easily disassembled and the contacts cleaned, which restored electrical operation.  Perhaps I'll be that lucky but I'd like to see if it works at all and propane seems to have given me some progress.  If it works on propane, I'll mess with the switches.  Unfortunately, it looks like to mess with the switches I have to pull the unit out - at least partly out to access them behind the control panel.  I don't see a way to remove the control panel inside the RV without doing that - unless someone knows different?

 

Thanks for all the help so far today.  I'm on the West coast, so have been able to mess with it until just now it's getting dark...

Edited June 19, 2023 by IdahoDoug

[linda s]

Maybe this will help

im272.pdf (bryantrv.com)

Linda S

[IdahoDoug]

Wow, thanks!!

[IdahoDoug]

OK, so here's what I've learned now.  And for other readers and liability - do NOT try this at home.

 

I have a gas leak from what I'm calling the manifold.  In the second picture above, it's the squared off object at picture center with a pair of nuts with blue thread locker paint on them.  When you push the knob on the front of the fridge while it's at the "gas" position, you open a valve in this manifold that feeds the burner gas, and activates the igniter. The burner lights and starts doing its job heating the ammonia solution.  My burner lights, then a few seconds later there is a whoosh as the leaking gas pool reaches the lit burner and causes a ball of flame a foot in diameter around the manifold.  I've had to do that about a dozen times to figure out what's leaking, as it only leaks when the burner is lit - not when it's off and everything is cooled down.  

 

What I needed to know was "Is it just the manual valve that's leaking when it is depressed, or is it a leak somewhere else in the manifold?"  This matters because if it's a simple manual valve, I could replace that.  If it's a leak elsewhere in the manifold then the entire manifold likely needs replacing.  So we had to keep lighting it and blowing out the fire (without accidentally blowing out the burner 8" away also) until we got it so the burner was working by itself.  Then, if it turned out the manifold keeps leaking after the manual valve is closed, we're going to get a fire again in a few seconds.  That happened, confirming the manifold has some major leaks.  Obviously, with that going on, I can't spray soapy water on the manifold to find the leak as I'd need to be very close and watching for bubbles.  Momma drowned all the dumb ones, so I'm not going to try that.

 

So, the fridge has to come out to be disassembled, and since it also doesn't work on electric, I'm done with it and it's not going back in. Had I been able to get it to work on propane and establish the ammonia fluids are intact and the basic system is functional, I'd have been happy to pursue cleaning the switches like that other member discovered and seeing if I could get it to work on electric as well.  Or, using it on propane only for a season.  Given this type of failure with a pretty scary foot diameter flame on a 40 year old appliance, I don't want to contemplate fixing a leaking valve, and then be laying there in the camper next summer thinking of the other valves in that fridge that might one day stick and also produce a huge gas flame.  All things considered, I'm pretty fortunate I did not burn down the camper before I realized I had a leak.  

 

So, if anyone needs spare parts for an Instamatic IM-433C, I'm located in North Idaho and would be happy to tear things off it you need and send them out just for mailing costs. The thermopyle flame detector works, the igniter works.  I'll take those off no matter what, as someone on here is eventually going to need those.  Thanks all for the hints, tips and information - particularly Linda!

[IdahoDoug]

Well, I next turned to the furnace, which was a piece of cake and works fine!  It would not respond to the thermostat, so I removed the thermostat from the wall, deduced it's simply the connection of the two wires that requests heat, so I touched them together and the furnace jumped to life.  I twisted them together for a half hour while I did other things on a chilly N. Idaho 55 degree evening and it got the interior up to 72 even with windows cracked for ventilation.  So, a victory for the day after all!  Replacing the thermostat is a piece of cake as it's a household type and there are even wireless bluetooth versions available with remotes, etc for not much money at all. My Sunrader is an earlier one so has no vents - just a powerful fan that blows all the heat from a single grille.  Should be just fine and I'll keep it.