Thermostat numbers fading

[Oranjoose]

I got back to my RV after 7 months and the display seemed to be fine when I first turned it on, but a few hours later when trying to turn on the air conditioning, the numbers aren't showing correctly (see photo).

The digits appear to be missing some of their segments, and are maybe fading some.

The air conditioning compressor is not kicking on either (was working 7 months ago when I last was at the RV), but I don't know if that's related to the thermostat.

What do you suspect the problem is?

 

[Sunnyfalls]

I would first confirm that it's receiving adequate voltage and then replace it.

 

[Larry N.]

That display looks like low battery voltage to the LEDs. Have you checked your house battery(ies)? I presume you're plugged in to shore power, but is it up to snuff? Is your converter working right? Hows the internal lighting? Does the microwave run, or the TV?

Do you have a multimeter? What voltage do you show at the AC outlets?

 

[Arch Hoagland]

Are you plugged into 30 amp or 50 amp shore power?

 

[Oranjoose]

Are you plugged into 30 amp or 50 amp shore power?

30 amp shore power. The RV houses a 12v battery that appears to be in good working conditioning.

I'm planning to go out and get a multimeter to be more well equipped to do further diagnostics.

Have any of you seen this particularly kind of problem with a thermostat? I'd expect it to be either on or completely off, or the buttons not work, or the temperature sensor inaccurate, or something like that, not these partially-displayed digits problem.

 

[Mark_K5LXP]

How emotionally attached are you to this thing? Meaning, you can attempt to fix but it might not be repairable, or survive a repair attempt. So my take on it would be to give it a shot, you have nothing to lose but have a backup plan for replacement.

LCD's are connected to their parent circuit board with a conductive silicone strip sometimes called an elastomer, or zebra strip. Over time contamination or oxidation can cause a bad connection between a circuit pad and it's respective LCD segment. One clue would be to push on the case with your thumb in various places around the display and see if you can observe different segments start to work again. The fix is to disassemble the unit, and carefully/gently remove the glass LCD by unsoldering or unbending it's metal frame tabs. Remove the zebra strips and clean everything with IPA and burnish the board, glass and zebra strip surfaces with a lint free wipe (lens paper, kimwipe) and IPA. Reassemble ensuring proper alignment and careful not to honk down too hard on the frame tabs or you'll crack the glass. 9 times out of 10 this action will restore proper function to an LCD display. If not, or if all this effort is excessive circumflatulation then chuck it and get a new one.

Mark B.
Albuquerque, NM

 

[Sunnyfalls]

Yeah, it's indicative of low voltage or failed display circuit board. You can't own a RV without having and knowing how to use a multimeter. Otherwise you will be paying much more money to others to deal with all the stuff that will soon need troubleshooting and replacing in RVs.

 

[gwinger]

How emotionally attached are you to this thing? Meaning, you can attempt to fix but it might not be repairable, or survive a repair attempt. So my take on it would be to give it a shot, you have nothing to lose but have a backup plan for replacement.

LCD's are connected to their parent circuit board with a conductive silicone strip sometimes called an elastomer, or zebra strip. Over time contamination or oxidation can cause a bad connection between a circuit pad and it's respective LCD segment. One clue would be to push on the case with your thumb in various places around the display and see if you can observe different segments start to work again. The fix is to disassemble the unit, and carefully/gently remove the glass LCD by unsoldering or unbending it's metal frame tabs. Remove the zebra strips and clean everything with IPA and burnish the board, glass and zebra strip surfaces with a lint free wipe (lens paper, kimwipe) and IPA. Reassemble ensuring proper alignment and careful not to honk down too hard on the frame tabs or you'll crack the glass. 9 times out of 10 this action will restore proper function to an LCD display. If not, or if all this effort is excessive circumflatulation then chuck it and get a new one.

Mark B.
Albuquerque, NM

It's not unusual for a display to start to loosen from the circuit board. Temperature changes and even pushing on the buttons flex the board.
Marks suggestion may work, but you have to be really careful when disassembling and reassembly. It may actually make it worse. I doubt it's a low voltage problem.

 

[John From Detroit]

LCD displays can also be damaged by heat and sunlight... LIke when you are NOT camping.... One of my radios works well because it was never exposed to sunlight except when driving (Curtan closed) and even then not direct generally and high heat.. NEVER.. (Full timer kept inside under 100º though occasionally not by much)_

Cars and closed RV's can easily get to 120 or more w/o A/C running

 

[SpencerPJ]

It might be as simple as loosening and retighten connections on both ends