AO Smith electric water heater keeps shutting off, e02

mike4500

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Joined
Jun 18, 2019
Messages
4
Location
NJ
Model Number
50 g
Brand
-brand-
Age
1-5 years
I have an AO Smith 50 gallon with the electronic display. I initially had to replace the lower element due to limescale. Once I did that and cleaned out the sediment, I had an e02 error code on the panel. I replaced the upper element, and then replaced the thermostat as tech support said that might be causing the problem. I am still getting the error code. I unplugged the electronic panel, and the unit functions for a few hours when I turn off the breaker, wait several minutes then turn it on again. However, a few hours later I get the blinking red light (2 flashes) and the unit stops heating water. The red high limit button is NOT tripped. I have tested the power at the thermostat and the elements with a multi meter and they all check out fine.

Any thoughts? I am at a loss.
 

Jake

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It sounds like the main control is malfunctioning, what's the complete model number of this water heater?

Jake
 

Jake

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Thanks,

I'd override the ESM first and see if the ESM is the culprit.

--->Overriding The Energy Smart® Module (ESM) If the Energy Smart® Module (ESM) is not working: Simply unplug the interface module and turn the set point knob on the Electronic Thermostat (ET) to the desired temperature (See Figures 9 & 10).

To replace a broken or damaged ESM module, see page 36 for ordering information.

Jake
 

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mike4500

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Jun 18, 2019
Messages
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Location
NJ
No, it's not. I had already unplugged the ESM and the problem persists. A little more information....sometimes when I shut off power at the breaker, let is sit for a while and then turn the power back on, it will do it's diagnostic cycle (blinking green light) and then start flashing red (2 times). But then sometime later it will start to heat the water and the green light will begin flashing rapidly. It may stay that way for a few hours but eventually the heater shuts off and the light flashes red (2 times) again.

I'm thinking maybe a short somewhere? Not sure how to test for that though.
 

Jake

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Possibly a short somewhere, check all your wires for frayed or cut insulation on them shorting out.

Jake
 

mike4500

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Jun 18, 2019
Messages
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Location
NJ
I checked all the wires and didn't find any problems, frayed insulation, etc. However, there is a four pin white plug in the water heaters junction box that I believe is the connector for the smart grid module, and two of the wires have come out of the pin/connector. I don't think this would have an effect like I am seeing though, and I never connected a smart grid module to the heater.

What I don't understand is why the unit keeps giving me a high temp limit code when it isn't heating up in the first place and the red reset button never "pops.".
 

Jake

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Ok, yes I really don't know, I rarely service these newer water heaters, so your best bet is to Contact AO Smith again to see what's going on.

Jake
 
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