FU code on fan mode with Dometic Thermostat

[snsaclark]

What does the "FU" mean on the fan LCD display on my thermostat? I see a different brand thermostat from Dometic (which is what I have) that says FU can stand for full keypad lockout. Someone else said it stands for "fuse" How do you unlock the Dometic keypad? I don't even know how it got locked in the first place.

[Bama Rambler]

What model of thermostat do you have?

I looked at both the Dometic single zone and two zone units and I don't see that code on either of them.

[snsaclark]

Yes...my manual tells me what "E" codes mean, but nothing about FU. If I click the "on/off" button it goes to "Fan" mode first where I get "FU". It used to say either AU for Auto or HI (high) LO (low). Then you could click heat and set a temperature or cool and set a temperature. Now Fan says "FU" and heat and cool shows an "E" code which is one of the error codes. I am hoping FU doesn't mean what I have commonly used it heard to imply, although that's what I thought of when my teeth were chattering because I was so cold!!!

[CHICKDOE]

could FU be AU with one segment burned out?

[Bama Rambler]

Which 'E' error are you seeing in Heat and Cool?

[snsaclark]

I don't think it is AU with a segment burned out. I bought the trailer new and have only been in it 5 days. One the FU appeared the E codes appear in heat or cool mode and you can't see the temperature. One had E5 and one had E9.

[Bama Rambler]

I'm sure you know this, but here are the error codes that you're seeing.

E5 - Open circuit or out of range Freeze Sensor. Air conditioner and dehumidification operation will be locked out. Heat pump, furnace, heat strip and fan operation can continue to operate but displays the last temperature set-point.

E9 - Invalid zone configuration. The dehumidifier DIP switch and either the heat pump or heat strip DIP switches are set to the ON position in one zone. Heat pump, heat strip, air conditioner, and dehumidify operation will be locked out in the affected zone.

From the description you gave, I'd say that your thermostat is failing. The FU is probably just a symptom of the failure.

Since it's a new unit, it's under warranty. I'd contact your dealer and let them look at it.