Three way fridge wont work on 120v

[tknick]

I have the factory installed dometic three way fridge in our PU.  While getting ready for a weekend trip, I plugged the frige in using an extension cord connected directly to the plug in the fridge compartment.  Shortly after plugging in, the GFCI breaker on my house where the extension cord was plugged in tripped.  I thought maybe the extension cord was bad so I changed cords with the same result.  I then changed outlets to one on a different circuit.  It too tripped the GFCI breaker on the circuit.

I connected my shore power cable, switched to 12v and the thing is working fine.  My shore power cable is plugged into the same circuit I started with and it has not tripped the breaker.  Any suggestions on how to trouble shoot the 120v circuit?  Is there any downside to using the 12v all the time and not even worrrying about fixing the 120v?

thanks

[wavery]

I have the factory installed dometic three way fridge in our PU.  While getting ready for a weekend trip, I plugged the frige in using an extension cord connected directly to the plug in the fridge compartment.  Shortly after plugging in, the GFCI breaker on my house where the extension cord was plugged in tripped.  I thought maybe the extension cord was bad so I changed cords with the same result.  I then changed outlets to one on a different circuit.  It too tripped the GFCI breaker on the circuit.

I connected my shore power cable, switched to 12v and the thing is working fine.  My shore power cable is plugged into the same circuit I started with and it has not tripped the breaker.  Any suggestions on how to trouble shoot the 120v circuit?  Is there any downside to using the 12v all the time and not even worrrying about fixing the 120v?

thanks

Did you try the 110v with the shore power cable plugged in?

Normal (so called) HD extension cords that you get from Home Depot etc usually have 16g wire in them. They are not intended for use on heating elements. You would need to use a minimum of 14g (12g is better) for a 50' extension cord. The GFCI (ground fault circuit interrupter) may have blown because the ground connecter on the extension cord (that center terminal on the plug) was not grounded to the trailer. You will notice that the plug on the fridge is only 2 prong. That is because the fridge is grounded to your converter through the grounding system in your PU. When you plug the fridge into the extension cord without using your shore power cord, you have no ground.

The  fridge works a little better off of 110V just because it offers more heat.

[mike4947]

The 12 volt heater is designed only to maintain the temperature of the fridge once it has been cooled by either 120 volt or propane and used for transport. It only has 1/2 the BTU capacity of either of the other two power sources.

 
You can start here: http://www.rverscorner.com/articles.html for articles on your fridge.

[tknick]

The 120v plug on my fridge is a three prong type and I was using a three prong extension cord.  But that doesn't really matter because I tried it using the shore power cord and the breaker tripped again so the problem appears to be in the fridge's 120v system and not in my house (thank God).

Am I correct that the 120v side is little more than a plug, switch and heating element?  If so, is there any way to check the individual components.  Or is this like going to the car dealer for repairs....well we replaced the dohickie, and that wasn't the problem so we thought it was the thingamabob and that wasn't it either.  so next we replaced the.....  If that is the case, should I just get replacement parts and start replacing...

Switched back to 12v and cooling like a champ.  Propane also works without problem.

[wavery]

The 120v plug on my fridge is a three prong type and I was using a three prong extension cord.  But that doesn't really matter because I tried it using the shore power cord and the breaker tripped again so the problem appears to be in the fridge's 120v system and not in my house (thank God).

Am I correct that the 120v side is little more than a plug, switch and heating element?  If so, is there any way to check the individual components.  Or is this like going to the car dealer for repairs....well we replaced the dohickie, and that wasn't the problem so we thought it was the thingamabob and that wasn't it either.  so next we replaced the.....  If that is the case, should I just get replacement parts and start replacing...

Switched back to 12v and cooling like a champ.  Propane also works without problem.

I still suspect that your problem may be in the ground circuit. Even if the plug is grounded, you could still have grounding issues in the camper. It is very common. Your GCFI is tripping because it doesn't sense a proper ground. That is what it is designed to do.

You might want to try plugging some other item into the extension cord to test your GFCI system. If that works, try grounding your fridge directly from the ground lug on the extension cord to a heavy piece of metal on the fridge. I

If you take the trailer to a repair shop, that is the first thing that they will try. Grounding issues are very common on RVs do to vibration and corrosion. They can cause problems that you would have never dreamed possible.

Once you have eliminated the grounding as a problem, you can move on to checking other wiring and switches for lose connections of faulty switches. Many people spend a lot of $ replacing parts, one at a time (like you stated in your last post), only to find that it was a grounding issue all along.

[Campaholics]

The GFCI trips when the current in hot is not equal to the current in the neutral.   When your body makes a connection between one of the wires and a ground , the GFCI trips before the current is high enough to cause harm.

I think some part of the circuit is touching ground.  Look for damaged insulation, including the white neutral wire.  A small nick will do it.
 
Bob

[tknick]

checking the grounding sounds easy enough and I will start there. The only other thing is it does not happen right away.  I can switch it to 120v and it will work for a little bit usually about 5 mins and then I hear the tell tale click of the GFCI.  Is that because the heating element has started up and the current gets to the point where it faults?

I guess why it happens isn't the most important thing at this point. I will start troubleshooting the ground when we get back from this trip.  Thanks for the help and $$$'s I am sure you have saved me.  The nearest service center is 120 miles away (according to dometic website).

Thanks again!