[Gapit]

I have a 10 cubic foot refrigerator freezer That pops the house breaker every time it goes into the defrost mode.
It works perfectly other then that. When its about 3-4 micro clicks before going into the defrost it will pop the house breaker.
I have replaced the defrost timer with a new one, Replaced freezer thermostat, even put a new fridge thermostat in..
Tried wiring in a 3 in 1 hard start as well...
I have removed and bench tested the defrost heater, It tested good. even wired it direct to 110 volt and it heated up fine.
I can disconnect the defrost heater and the fridge runs great, Plug the heater element in while the defrost timer is in defrost mode and it will pop the house breaker.. What am I missing???

 

[surferdude2]

Disconnect both heater leads and check the resistance from one of the heater leads to the metal sheath. Sometimes they get shorted internally and will still work on the test bench since they're not attached to the grounded cabinet or have contact with the evaporator coil.

 

[Gapit]

Yes, I have tested Continuity from both leads to the metal sheath, both had No continuity. Tested continuity between the two leads read 38.

 

[Gapit]

I live in Vancouver WA

 

[surferdude2]

It could still have a ground fault and not be detected by the low voltage that an ohmmeter probe presents.

Test by plugging only one lead plugged in... if it doesn't trip... unplug that lead and test with the other one (in its own socket)... if neither trips it... plug both leads in... if that trips it... the heater is likely grounding out as soon as the temperature increases slightly. Get a new heater.

 

[surferdude2]

Another quick test you can do... support the heater on a glass dinner plate so it doesn't contact any other metal.. if it doesn't trip using that method, you can be sure it's grounded internally.

 

[BayouRunner]

Don’t think the ohms should read that low. Most heaters measure in the 300 to 400 ohm range. We recently had a refrigerator that would trip the breaker on defrost and it was the cabinet wiring. Manufacturer gave them a pro rated amount towards the purchase of a new frig. Have no idea how much.

 

[surferdude2]

The 300 to 400 ohm range is likely for the door mullion heater. That wouldn't be nearly enough heat for defrosting a freezer coil. That would be 400 ohms = 36 watts and 300 ohms = 48 watts at 120 volts.

Most of the defrost heaters are much higher wattage, around 375 watts +-.

375 watts / 120 = 3.125 amps.

120 volts / 3.125 amps = 38.4 ohms.

The OP reports 38 ohms so there's no problem there unless it has an internal line to sheath short that grounds the hot line to the grounded cabinet.

I can't imagine any other reason for the circuit breaker tripping only if the heater is plugged in. That puny 3&1/8 amps won't trip a 20 amp breaker under normal circumstances.

 

[Gapit]

I have suspended the heater in the freezer compartment away from touching any metal and rotated the defrost timer into the defrost mode and plugged in the fridge. It did NOT trip the house breaker......
Time to buy a new heater element..
Thank you so much for your help.....

 

[Gapit]

Brought the freezer down to operating temp, Rotated into defrost mode, element started getting hot. Carefully used a screwdriver and touch the element to the evap. coils and it immediately popped the house breaker.
Problem solved!
Buying a new defrost element.

 

[surferdude2]

Do yourself a favor, DON'T EVER DO THAT AGAIN!!!

You were very lucky that the short you created to the evap coil didn't blow a hole in it! That would be a more expensive repair but that isn't the worst of it... the refrigerant blowing out will be loaded with atomized oil and can ignite into a huge flame thrower that will make your face unrecognizable to your own mother, if you happen to survive.