Thinking of installing a 12v relay to isolate my Dometic cube frig from the Batt. when the engine is off. Reason: The frig LP flame goes out when traveling. This would be used sparingly for short runs not for continuous use. I know I could flip the switch. When camping I would switch to LP. Any suggestions?

Small ice cube sized relay from auto parts stores would fit your bill. I would wire it into an ignition switch hot in run position. It would take an extra wire.Before doing this I would attempt to find out why the refer blows out.Are the flame covers in place? Have you checked to see if the flame sensor is real close to the flame and in direct path? If yes try using a secondary heat shield. Even a piece of aluminum foil may help.

enblethen wrote:Small ice cube sized relay from auto parts stores would fit your bill. I would wire it into an ignition switch hot in run position. It would take an extra wire.Before doing this I would attempt to find out why the refer blows out.Are the flame covers in place? Have you checked to see if the flame sensor is real close to the flame and in direct path? If yes try using a secondary heat shield. Even a piece of aluminum foil may help.X2 I believe you want a NC relay that opens with the ignition on.Not sure this is necessary as the propane should shut off when the flame goes out.

Personally, I would correct the flame going out. Another question I have, is what kind of Fridge do you have (make and model)?I think you would get more responses from the Tech Forum, so I am moving this Thread from the TC Forum.WayneModerator

OP: I just looked at your profile.Is the refer in question in the pop up camper? Some pop ups do not recommend running refer on propane while collapsed.If it is does the refer have two vents when collapsed?Is this a three way refer?Make and model of refer would help.

We run ours exclusively on 12v when on the road. Did it for 8 years before adding auxiliary charge line and ignition controlled relay to shut off refer with truck. Running out immediately when stopping for 5 min to keep batteries from discharging got old. Also shutting down refer last hour or to ensure batteries charged when arriving at camp. Adding the ignition controlled relay simplifies usage on 12v, running auxiliary charge line makes it more practical as far as battery charging and refer 12v use. We also now have solar-running the refer on 12v just is not an issue. Running on 12v is the least efficient but it does work. That said as MOST will tell you you cant or shouldn't so I would be hesitant to recommend. Why it worked for us and seemingly no one else, especially for the 8 years prior to upgrades, I cant say.Couple of thoughts- Verified you have sufficient 12v supply to run refer when truck running? Looking back it appears you've added 10ga charge line. Have you tried to run the refer on 12v while traveling and can truck keep up? No sense going to effort of relay if it kills your batteries and milk is still warm? Second is you said "sparingly for short runs not for continuous use".. If thats the case, the refer pre-cooled & closed will keep cool for a few hours with out running at all. Third have you verified that refer will respond as you expect. IE set to run 12v, once on- disconnect the 12v source, pause then reengage-Does refer come back on in 12v mode. Some when source power removed then reapplied the board will default to off position. (so running a relay wont work). IF you decide to add the ignition controlled relay, Id recommend adding manual switch to relays ignition trigger wire. Also, though it is as simple as adding a ign. controlled relay, you'll also need to run a 12v source selector switch, either directly to battery as normal for propane use or thru the relay. Could be as simple as an on/off switch (30amp toggle) on source line with the relay as a bypass.

12 Volt Frig Relay | Good Sam Community

niftypkg
Explorer
Dec 05, 2013
Mondays test flight. After the countdown I flipped the 12v switch and it fired up. Liftoff looked AOK on the way to the first rest stop. Flipped off the 12v power and switched to LP. Frig fired up and stayed that way for 2 days. I suppose engineering fixed the shut down problem with the wind shield placed adjacent to the gas pipe. Looks like it is Go-go from here on.
enblethen
Nomad
Dec 01, 2013
Is the top vent out the top of the rig or out the side?
If it is outthe side, make sure there is a deflector at the top of the refer cooling unit to angle tha ir flow toward the vent.
niftypkg
Explorer
Dec 01, 2013
This TC is a Sunlite popup and the refer vent is exposed with the roof down. The refer is model# RM183. emblethen the heat deflectors in the vent are in place. What I meant by 'sensitive' thermocouple is that the test voltage increases rapidly when the flame lights. The thermocouple is over the flame so that is not any problem.
niftypkg
Explorer
Nov 30, 2013
As per the advice provided here, I checked out the heating element after hooking up the (+) to the battery block terminal (temporary until I get a relay) and got heat. I made a baffle to block the wind from blowing out the flame. The test will come Monday.
enblethen
Nomad
Nov 30, 2013
What do you mean about the thermo couple being sensitive? You may need to adjust it to get it more into the flame.
Is your upper vent for the refer in the portion that raises or is in the lower section? If in the lower section of the rig, look at the top of the refer from the oustside. Insure that the air flow has a deflector so the air moves out rather then gets "trapped" in a void area.
Reddog1
Explorer II
Nov 30, 2013
I strongly believe there is something amiss with the baffling.

Perhaps I was too quick in moving your thread, someone with the same camper and Fridge may have or have had the same problem. Perhaps I just missed it, but what is your TC type?

Wayne
j-d
Explorer II
Nov 30, 2013
Those "cube" (some call them "Bosch") relays have both types of contacts. Using the "NC" contacts (so it OPENS the fridge power with vehicle ignition source) would make the default to be Fridge ON.
niftypkg
Explorer
Nov 30, 2013
enblethen L/P components look OK. Thermocouple checks out but seems a little sensitive. Flame checks out and wind baffles are all present and accounted for.
niftypkg
Explorer
Nov 30, 2013
Reddog LP operation seems to be OK generally but with cross wind not 100% reliable.
niftypkg
Explorer
Nov 30, 2013
AVEV942 been there done that. No I have not tested the frig on 12v operation because I finally found the + wire. Good idea to look before I leap.

Forum Discussion

12 Volt Frig Relay

About Technical Issues

Related Content

12 Volt Frig Relay

12 volt fridges

Buzzing relay

Relays under the hood?

Domestic frig in 2002.....replacement available??