Dometic M50 Thermocouple
 

On the road and the thermocouple on this M50 has failed. For those of you who did not give up on your M50, how have you handled replacing it with current off the shelf TCs?

This is a very good working and in good condition old fridge in my 60 Tradewind. I would like to figure this out. Al the threads I can find are old and just say replace it. I would prefer not.

Thanks! Richard

send me a pic . I am looking for a click fast for a 76 in a 62 tradewind .
have it working with an electric element clamped to clickfast post and t-stat install inside ( out of rm 7030 ) customer would dearly love too get gas going again but won't mcgyver lpg ! have several old thermocouples so maybe . got a working clickfast ?

Here is the thermocouple from the backside and the other end as it screws into the gas flow control. The threads, type & size of the opening is unknown and will hv to wait till I hv my full tool set at home but by the looks of it there are options for adaptations. I do not know if this is the stock thermocouple but the control valve looks original. Thanks for your help.
Attachment 305407Attachment 305408

Good luck finding a thermocouple. I have an M50 in my 62 overlander, and converted it to 12v using a danfoss compressor, evaporator kit. It works great and I get to keep that beautiful vintage look.

Can you tell me more abt your conversion? Tnx

https://www.suremarineservice.com/ice-box-conversion-components.aspx

See link above for the kit I used, using a flat evaporator. The compressor fits under the fridge, install through the opening vent door. You will need to drill a 1” diameter hole to provide access for the cooling lines and thermostat wires.

It’s really pretty easy.

I’m out of town right now, I can send some photos in a week or so.

Sure like propane and do not carry enough battery to source the current needed for that dc conversion.

Dometic M50 Thermocouple
 

I have not dissected the existing thermocouple but since it’s not electrical it must be creating mechanical movement at the actuator end which controls gas flow. Is this right?

The thermocouple is an electrical device. It generates 20 milivolts which is needed to open the gas valve.
If the tube/piping is not compromised you may be able to disconnect it from the gas valve and clean the contact points. Both at the thermocouple tube end and inside the gas valve.
Be sure to push it in the gas valve when reinstalling. Do not over tighten it.
The flame end may need cleaning as well.
Be sure the flame end is located in the flame.

TG Twinkie this is good to know. I’m hopeful, when I get home in a few weeks I can disassemble the gas flow control and interface an off the shelf TC to it. Seems there are numerous TCs with a couple of wires coming off them.

Send me a pic of the back of the unit. There won't be any wires on the thermocouple. It will just be a small copper tube.
This type of thermocouple is used on household gas water heaters and are available at well stocked hardware stores.

I posted a pic of the back of the valve earlier in this thread.

Forgot you posted pics. In the top pic I can see flame so you have gas.
Are you travelling with the coach?

Yes to traveling with it and I hv the light button jammed to keep it lit. I’m the control for the interim. [emoji43]

That is VERY dangerous!!! The gas valve will not close if the flame goes out.

Yes, I only light it if I’m in the coach and keeping an eye on it. It won’t do for unattended operation.

An update: the thermocouple once removed and tested put out well over the 10mv needed. But the end of the thermocouple going into the gas flow control was corroded. Once cleaned and reinstalled the good ol M50 fridge works perfectly.

Attachment 307129

Attachment 307130

Glad my suggestion of cleaning the contact points at the gas valve worked.
Makes me wonder how many refers were replaced because of this problem.
Travel Safe

Thanks for your suggestions too. They were helpful. Imo, even if the thermocouple goes bad, a new sensor, a modern exposed wire sensor can be spliced into the original thermocouple end which fits into the controller.

Additionally, like you, I feel there must be a compatible replacement otf. Now that I’ve seen this thermocouple and its connector I’m on the lookout. [emoji4] glad to hv this unit back as it wks well and fits this Tradewind in every respect.

The link no longer works. I have researched electric conversions and see kits from Norcold, Nova Kool, Isotherm and others. Which did you use? Were you also able to keep a working freezer with the flat plate evaporator? I see some sell a box shaped evaporator that forms a new freezer, but I think you'd have to remove the original freezer to use them.

Photos would be appreciated.

https://www.suremarineservice.com/s.n...gory.318481/.f

Try this link above. I used a vitrifrigo conversion kit. Works great. No freezer with a flat plate evaporator, but they do offer a "boxed" evaporator that should fit in the freezer.

My propane system still works somewhat, when it is very hot outside or want to cool down quickly I run both the propane and 12V compressor at the same time.


I'll send some photos in a bit.

See photos attached:

(1) Outside of M50 fridge, (2)inside of fridge showing evaporator plate on back wall (looks like I need to defrost it!), coolant plumbing and thermostat and 1" hole I drilled in the bottom, (3) photo underneath the fridge showing compressor install (a little dark)

Thanks. And thanks for the photos. Interesting to install the electrical cooling plate and keep the gas system. I had not considered that option. I am still researching options for my 1962 Safari with an M50, which include trying to get the original gas system working, converting to electric, or having the fridge upgraded to modern controls. I guess I should add the hybrid system you went with to the options list.

the end of that thermocouple looks like a normal one you see at lowes or homedepot in the water heater section.. only difference is the thread is course as most are fine thread I find. we have a convertor that adapts the threads. so of them are are US threads and some are European threads.