2025 Montana 3123RL Electric Water Heater Has No 120V Power

[Julesrn2]

Hello,
We just bought a new 2025 Montana 3123rl. Have it out camping. The (16 gallon) electric water heater is not working (thankfully the propane does).
We’ve checked everything. Element is good, thermostat good, doesn’t need reset. My husband has found there is no power getting to it from the inside. Interior Rocker switch lights up. There is no on/off toggle outside on unit to the lower left (or anywhere else) as was suggested to check in other forums.
Is there something else we aren’t checking?
Are there any known issues for the newer Montana's regarding electric water heaters?
Thanks

 

[twindman]

If you ever plugged in the power cord and the water heater was dry, it is toast.

 

[ChuckS]

Since hubby verified the heating element is good ( used a multi meter ) I gather and has no power to the 120VAC side I would check:

1. is the electrical cord from the water heater plugged into a working 120 VAC outlet
2. If YES then the next item to check is to see if 12 vdc is getting to the remote relay that controls 120 VAC power flow
.. this is located on the top back side edge in a small junction box...
.. the relay is notorious for overheating and melting

 

[ChuckS]

Remote Relay for Suburban series WHs

 

[Julesrn2]

If you ever plugged in the power cord and the water heater was dry, it is toast.

Nope, element good. Thanks
We’ve been camping for 20 years.
If it was bad it would have happened at dealership as we just bought it. Didn’t turn on til we got to campground and water hooked up (water heater full)

 

[Julesrn2]

Since hubby verified the heating element is good ( used a multi meter ) I gather and has no power to the 120VAC side I would check:

1. is the electrical cord from the water heater plugged into a working 120 VAC outlet
2. If YES then the next item to check is to see if 12 vdc is getting to the remote relay that controls 120 VAC power flow
.. this is located on the top back side edge in a small junction box...
.. the relay is notorious for overheating and melting

Thanks, will look into this.

 

[Carl n Susan]

An easy 1st check, before pulling the WH to check the relay is to measure for 120V going into the left thermostat (120V side). If there is 120V, then there should be 120V power out of the T stat assuming the water in the WH is cold.

No 120V to the T stat pretty much assures the relay is bad.

 

[BB_TX]

To add to the info above. There is a 12 vdc side and a 120 vac side to the circuit to energize the heating element. Schematics of each attached. One shows the relay coil and the other the relay contact. The 120 vac schematic shows a switch mounted on the WH. Some have it and some do not.

The inside switch sends 12 vdc to energize the aforementioned relay. And a contact from that relay sends 120 vac to the thermostat on the WH.

If you do not get 12 vdc to the relay it will not work and no120 vac. And of course if the relay is bad then no 120 vac. And someone posted one time that their WH actually had a standard power cord plugged into a 120 vac outlet behind the WH. His had come unplugged and thus no 120 vac.

If the relay is working then you should get 120 vac to the thermostat/hi temp cutout, then the element. The thermostats have been known to go bad. And burned wiring also a common problem.

Another problem has been burned wiring at the relay itself.

Another possibility that has been reported in the past is loss of neutral to the WH. 120 vac was actually there but with no neutral it will not work. When checking for 120 vac at the WH put your meter ground lead on the metal case rather than the neutral wire on the heating element. That will check that possibility.