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KRFC300ESS KitchenAid Refrigerator - auto-defrost mode issues

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RustyShackleford

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Model Number
KRFC300ESS
Brand
KitchenAid
Age
1-5 years
Not exactly a repair issue, but ... I am setting up an EV-connected 1000watt inverter to use for home backup power during grid outages. Looks like it should be able to easily handle my refrigerator (KRFC300ESS) and a couple of other circuits. I measure the fridge at 100+ watts, maybe double that on startup, and the energy placard gives an average power of 64 watts (563 kwh per year). EXCEPT, I've heard that the auto-defrost uses quite a bit more power (makes sense), I'm thinking I've read maybe 500 watts or so. So several questions:

1. How much wattage does auto-defrost mode actually use and how long does that last ?
2. How often does it go into auto-defrost mode ?
3. Is their a way to temporarily disable auto-defrost, failing that, a way to "discourage" it from happening ?
 
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rickgburton

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RustyShackleford said:
How much wattage does auto-defrost mode actually use and how long does that last ?
440 - 490 watts. Pulsed defrost heater is on continuously for the first 5 minutes then off for 60 seconds then on for 120 seconds and continues with the on off cycle until the defrost thermostat opens or a maximum time 20 minutes.

RustyShackleford said:
How often does it go into auto-defrost mode ?
Adaptive defrost- The control uses information from the thermistors and keeps track of number of door openings, compressor run time and length of time the defrost heater was energized during the last defrost cycle to know when to start the next defrost cycle. That can be anywhere between 9 and 99 hours

RustyShackleford said:
Is their a way to temporarily disable auto-defrost, failing that, a way to "discourage" it from happening ?
There's no way to disable it by the onboard program. You can disconnect one of the element wires but that will cause other problems that if disconnected long enough, reconnecting it alone may not bring it back to normal cooling mode. You may need to unplug it for 24 hours or defrost the evaporator with a hair dryer.
 

RustyShackleford

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Thanks, Rick. Guess I'll just try to not add more than 500 or so watts of load beyond the fridge, and/or deal with the inverter dropping out if auto-defrost comes on when I am drawing too much elsewhere. It'd be fun to try to rig a warning light for when auto-defrost is active !

Since only having 1000 watts obviously means I'll shut off big loads (like HVAC, water-heater, well pump, EV charger), maybe I won't have all that much left anyhow. Some lights, pretty much all LED, and a ceiling fan or two if it's a hurricane outage (we get those as well as winter-storm outages, lucky us).
 

rickgburton

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RustyShackleford said:
It'd be fun to try to rig a warning light for when auto-defrost is active !
Connect an indicator light in parallel with the defrost element. The indicator light will turn on everytime the element is energized.
 

RustyShackleford

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Messages
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Well, had a power outage tonight and hooked my 1000 watt inverter to the EV again. The refrigerator overloaded the inverter - the inverter shut off (and made a useful but super-annoying whining alarm). This was even with no other loads connected. When I got this working a few months back, the inverter drove the fridge just fine even with some other small loads also being driven (and with the fridge compressor cycling a few times).

So I have to think the auto-defrost is the culprit. I want to be able to disable it, short-term while the inverter is driving it during a power outage, and without dragging the fridge out and taking the back off. IOW, some kind of switch I can access from the front (hopefully non-dangerous voltages). I'm an electrical engineer, and I've gone into this fridge before (another story); so I feel that with the right advice from you good folks, I should be up to the task. Any ideas ? TIA !
 

rickgburton

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I feel that with the right advice from you good folks,
Sorry my friend, I specialize on appliance repair, not appliance modification. My advice to you would be don't modify the refrigeration. Maybe one of the other guys will have some useful information.
 

RustyShackleford

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Messages
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Rick, can you tell me where the evaporator coils, defrost heater, and defrost thermostat would be located ?
 
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