Refrigerator on electric keeps blowing 20amp breaker

Lizard59 · 05-04-2019, 09:20 AM

I have a 2005 Trail Manor 2720SL. Bought it a year ago. Recently the Norcold refrigerator on electricity keeps tripping the 20 amp breaker. Replaced the breaker but it keeps tripping the breaker. The refrigerator works fine on propane
Any suggestions?

**rickst29** · 05-04-2019, 12:25 PM

The most likely problem (by far), is a short-circuit within the DC heater coil.

The "input" and "output" leads to the DC heater consist of two yellow wires. Disconnect these wires from the DC heater unit, and measure resistance of the heater core. The Resistance should be right around 1.0 ohms.

If resistance is less, the heater core has a short circuit and needs to be replaced.

If resistance of the heater core is correct, THEN the problem is within the rotary dial switch OR the yellow lead wires. With wires disconnected from the heater, verify that resistance between them is infinity. IF IT IS NOT, then the "hot" lead wire has a fault to Ground - either within the switch, or somewhere along the wire. I'd carefully inspect the wire, and then blame the switch (replace it).

To actually verify switch failure - BE CAREFUL DOING THIS: Install a 3A FUSE in place of the TM load center 20A fuse (you DO NOT want to allow 120W of power through your body!) Remove both yellow cords, and put a voltmeter across the terminals. Then flick the rotary dial to "12V Mode". If the TM fuse blows, there is a short inside the switch. If the TM fuse does not blow, and the Voltmeter shows ~12V, then the short occurred within the yellow wires.

Shane826 · 05-04-2019, 01:53 PM

Would a DC coil short cause and AC circuit breaker to trip? I’d think that would blow the DC fuse...

**rickst29** · 05-04-2019, 03:21 PM

If it were a "fridge on 120VAC" problem, then the very first thing which should have blown is the 3A fuse within the Fridge (rather than the 20A breaker in the TM). The 120VAC "hot" wire doesn't even reach the switch before going through this fuse! If the fuse has been bypassed - restore the fuse first. Then test to find problems, using a voltmeter measuring resistance - with the selector switch set to "Off". 20A *120V is 2400 WATTS, that can kill you almost instantly!

Nope. DC operation has nothing to do with 120 VAC power at all. (120VAC operation, OTOH does depend on 12VDC to run the control board and work with the thermostat.) I might have confused "AC Breaker" with "DC Fuse".

- - - - -

Lets see if Lizard can clarify. He did talk about "replacing the breaker" - but Breakers are reset, not replaced. At the same time, "Fuse" is a lot shorter to type, so I'm not sure what to think.

If a former owner bypassed the 3A fuse, that is a very bad thing (TM), it must be replaced FIRST. Tthen the downstream problem problem needs to be fixed. Wiring diagram shown in the photo. There are 4 possible points of failure:

#1, a short circuit in the heater coil (the 120VAC heater should have DC resistance of about 140 ohms). Disconnect both leads and test this between the two terminals. Also test that resistance from EACH terminal to the fridge frame is infinity.

#2 a short circuit within the Selector dial, leaking 120V "hot" to Frame "Ground", instead of connecting only the black wire into the thermostat. This can be tested by disabling the TM circuit breaker, VERIFYING the 120V terminals at the fridge are "cold" - and then testing resistance between the 120V input wire to the selector switch and the body of the Fridge. It should be infinity. Now proceed to turn the mode switch to 120V. Test that resistance again - it should still be infinity. If it isn't, then your fault lies within either the Selector Dial or the Thermostat. Turn the "mode switch back to 'Off', and test the Thermostat in isolation.

#3, It could be a be short circuit within the thermostat, where 120V is connected to the fridge frame (leaked to "Ground", rather than connecting only to the downstream 120VAC "hot wire" (Color = Brown) when the switch is enabled (and closes the circuit). The "thermostat" runs propane mode by setting the flame orifice, directly from the dial position. 120VAC is only present when the "selector dial" (part #17 in diagram) has been turned to "120VAC" operating mode.

This can be tested without actually presenting 120V power: With the "temperature" dial is set to 1, the resistance between the 120V Black wire "hot terminal" (WHICH MUST BE COLD IN THIS TEST!) and the metal body of the thermostat must be infinity. The resistance between the Black and Brown wire terminals must also be infinity, AND the resistance between brown terminal and thermostat body must also be infinity.

Then, turn the selector dial to "12V mode", and turn the "thermostat" dial to 6. While turning the dial, a tiny "click" should be heard when the thermostat closes the circuit between black and brown. The resistance between black and brown should now be zero -but most important, the resistance between the brown wire terminal and the metal body of the thermostat must also be INFINITY.

#4 a fault in the Brown wire (leaking to ground).

oldstick · 05-04-2019, 05:19 PM

Agree it could be a problem specifically with the fridge, but first check the 120V wiring junction boxes outside and on the left side of the camper. A bad connection inside those boxes is common with road vibration and could cause a short circuit and breaker tripping no matter which appliance is affected.

Lizard59 · 05-04-2019, 05:37 PM

Initially we thought the 20 amp circuit breaker was bad because it would not reset. So we replaced it. It’s possible it wasn’t bad because we had the same problem today. We could not get the circuit to reset. So we switched to propane.
After many tries we got it to reset.

Thank you for all the good information

Shane826 · 05-04-2019, 10:27 PM

There is a junction box outside below the fridge. That likes to get water inside, and cause some issues. If a breaker doesn’t reset it’s usually because it’s doing it’s job.

**rtcassel** · 05-05-2019, 07:09 AM

Is it possible that the problem is in the hot water heater? When the element has burned out due to no water in the tank, other problems have been reported, if memory serves me correctly. The fridge and hot water are on the same circuit in my TM.

oldstick · 05-05-2019, 07:42 AM

Quote:

Originally Posted by Shane826

There is a junction box outside below the fridge. That likes to get water inside, and cause some issues. If a breaker doesn’t reset it’s usually because it’s doing it’s job.

Quote:

Originally Posted by rtcassel

Is it possible that the problem is in the hot water heater? When the element has burned out due to no water in the tank, other problems have been reported, if memory serves me correctly. The fridge and hot water are on the same circuit in my TM.

Agree with checking both of the above.

Lizard59 · 05-05-2019, 08:58 AM

Thank you for all the tips. We are currently camping. We don’t have all tools needed to check these options but will check when we return home

We checked the 120V box area and no water seen.

Yes the fridge and hot water heater is on the same circuit.

We’ve been running the fridge on propane and now the propane is not holding as of this am. The gas is working on stove and hot water heater.

Is there a correlation between the gas not staying on the refrigerator and the 20amp circuit breaker tripping?