Lennox 10F81 iComfort WiFi Thermostat LCD Screen Replacement Guide & Display Issue Diagnose

[@ekasusilo]

Did you try to replace the 1.5F super cap as well?

[@TheGizmoGarage]

I did not, I tested voltage on the super cap and it's at 2.8V, thought it was the rechargeable button battery they use to store time data like on PC motherboard, didn't realize it's actually a capacitor. I looked at the soldering and it seems to be a lot harder to replace.

[@ekasusilo]

@@TheGizmoGarage I ordered a replacement 1.0F 5.5V from Amazon and will let you know how it goes.

[@ekasusilo]

@@TheGizmoGarage I managed to replace the super capacitor, it was leaking badly. I had to do a lot of cleaning, then soldered the new super capacitor and voila, it is alive! However, when I see the white and grey screen with lines like in yours, it is already too late and the damage on the board is unrepairable. The voltage across my super cap is basically zero, so there is damage on the charging circuitry, or perhaps it takes some time to charge it.

[@ekasusilo]

BTW, I found the exact replacement part on Digikey, but shipping cost is too high. So, I found a similar replacement from Amazon, 1.0F 5.5V, a pack of 6 for $10 in the U.S.

[@TheGizmoGarage]

​@@ekasusilo Thanks for the update! I pined your comments so others could take this into consideration on their repair as well!

[@raisam2159]

@TheGizmoGarage I really appreciate your video and answer to my question. After watching your video and reading a large number of posts recommending to replace capacitors, I decided to figure it out for myself. I purchased several none-working units to fix. Smaller 220uF and 47uF capacitors test good in all of them. It was measured with both ESR meter and measuring AC component on those filters. Examining about 5 different thermostats revealed that the super-capacitor is leaking on all of them. Even though it isn't very obvious at first, there are wet areas around it. My initial goal was to re-flow a BGA chip that controls the display and all peripherals, however before I did that, I measured all of voltages going to the screen. One voltage was missing. It took me a long time to figure it out without the schematic, but I finally did it. Some supply voltages never reached the screen. On all units that I have the internal trace and corresponding vias were damaged by either the acid or it was poorly designed from the beginning. I was able to run a jumper wire to fix the issue. One of the most difficult issues was sourcing and replacing the supercapacitor. Apparently, there are multiple types of H-type with leg width of 0.8mm and 2mm. The board is also very thick, so you need to preheat it in order to replace the capacitor.

[@georgeharden-hd8qk]

Lance, Minutes 3.5 to around 8.0 of this KZbin video, a over achiever customer made of his experience with his Lennox iComfort KeyPad really helped me. I finally got the air-conditioning unit you got for me back on line finally. Hopefully it is a permanent fix.

[@coreypfenning7396]

Does anyone have a link to a replacement LCD? Im not finding anything on Amazon or eBay. My thermostat works with the app, the display is just a blue fuzz.

[@hueric4849]

My suggestion is turn off the AC from the indoor unit for several hours so that the wifi will be lost in the thermostat when weather permits. When you put it back on, the screen will be normal. NEVER connect it to your wifi. For my case, I changed blower motor every 2 or 3 years for the past 10 years. My system was installed in January 2014. My AC system is out of warranty in January 2024. I had error 201 from the screen (blower motor problem) in February. I turn the thermostat off for 1 hour and turn it back on. then I connected the thermostat to the wifi. The same problem happened again. same probem occurred several times. At last, I decided to turn if off for several hours, then turn it back on. I did not connect my 10F81 thermostat to the wifi this time. Everything is back to normal until now (it has been 8 months). I had bland/white screen several times. I bought a new one 5 years ago and I have 2 wifi thermostat. I exchange them if one is white screen. After exchange the thermostat for sometime, the one had blank screen works again. maybe the capacitor was discharged over time? I don't know. I suspect that the company did something to the screen or the blower motor so you have to spend the money, at least for mine. NO MORE LENNOX! NEVER AGAIN!

[@skas8971]

Mine was white, not sure what you guys mean by shades of grey but some areas could be considered grey and shadows of the original buttons that show when its working properly. Replacing the caps worked fine. Didnt have to replace touch screen. Not sure why youre telling people they have a bad board when the cap fix will likely work for most of them.

[@skas8971]

Additionally, most people have the version that has the 3 small caps or the 2 larger caps. I believe you're the only 1 I've seen that jad 2 large 1 smaller. Fyi, the small caps and large caps are all same voltage and same capacitance. The larger ones have a slightly wider temp range but that's not that important. If you're good enough to make sure all the necessary contact is occurring on the pads you can replace the large ones with the smaller ones, although if you're buying caps it's probably better odds to just get the larger ones.

[@skas8971]

I didn't see the end of your vid before leaving the above comment. Those shades of grey are much different than mine. Mine are very subtle and not striped from top to bottom like that. Mine were more likely caused by the shadow of the original colors behind the white... like where it's very dark blue or black.

[@skas8971]

A couple of days later after the cap swap the white screen has returned. I'm thinking maybe it was fixed temporarily just from cleaning the board, etc not from the cap swap. Ive found someone who replaces the board and eliminates the problem parts and I'm buying a mew 10f81 from them since the s30 and s40 have so many problems and 2.2/5 stars on lennox's own site. Thanks for your vid.

[@alanm5013]

@lireviews : So do you now have a working display you might want to sell? I fixed a 10f81 with leakage damage from the super-cap (the most likely failure mode, apparently), but there's an intermittent in either the display or the flex cicuit that connects it.

[@TheGizmoGarage]

I don't, you may be able to find one locally on facebook marketplace

[@leocan9591]

hello please share link for how to replace caps on this model?

[@kenstumpe9612]

Excellent video with real technical content. My upstairs secondary furnace thermostat just went down. It was working fine, but the furnace power got cycled and suddenly the thermostat only shows three cycling dots. I feel the screen is fine and it must be not booting fully. Do you have any experience with connecting to the USB port?

[@TheGizmoGarage]

I have no experience with connecting it to a USB device, and I assume only Lennox technicians have such software to run diagnostics. You can try to do a reset by cutting off the power to the thermostat to force it to do a new reboot.

[@sanm9939]

Hi, I’m glad I found your tutorial!!! my touch screen has lost its colour and it almost looks black and white. It’s not connected to the wi-fi so I can’t switch it on even though I can see the on button control. Also can press the settings button and it kind of transitions very very slowly to the settings screen. I’ve reduced the background intensity so I can see the screen a bit clearer. Do you think it’s the capacitor or the screen that’s the problem. We had to switch off the power today and when we put the power back on the screen was white with black stripes. We unplugged and replugged and now it’s just black and white but we can see the controls even if they don’t work. Thanks and I hope you can help me!

[@TheGizmoGarage]

Shortly after I changed my screen with a replacement unit, it broke again. I have to spend $1000 to upgrade to the newest Lennox S40 thermostat, which comes with a 10 year warranty so we can have a peace of mind.

[@sanm9939]

I just pulled it apart like you did and put it back together and now it’s working??? Maybe something just dislodged? Don’t know how, cause we didn’t even touch it when we switched off the power today. I think we better start saving cause I feel this may be the start of it breaking down permanently and I don’t want to fork out $1000 in one hit. Thanks again for your video cause at least you taught me how to safely take it apart.

[@TheGizmoGarage]

@@sanm9939 No problem, glad it's working, at least setup the Wi-Fi to make sure it's working on your phone, so even if it goes dark it can still work for a while

[@sanm9939]

@@TheGizmoGarage for some reason the WiFi isn’t working. It’s connected to my home Wi-Fi but not connected to the server. Ugh! I’ll have to call Lennox on Monday and find out what’s going on!!!

[@zackmollick]

So I just bought a used unit off Facebook my old screen was doing the white screen but the new unit it gives me a communication error what did you all do with the as card I took them both out and put my old unit in my new unit and now I get 11 errors do you remember how you got that working correctly?

[@TheGizmoGarage]

They maybe different versions of the firmware, whichever one will take you to a setup page you can reconfigure the settings through the setup menu by long pressing the "lennox" logo on bottom right corner

[@raisam2159]

When I apply 24VAC, thermostat boots to System Alert error 12: incomplete system. There is an X in the right top corner that when touched will reboot it to the same state. How do I get it to home screen?

[@TheGizmoGarage]

I don't know... Sounds like the wires are not hooked properly to the back plate. I'm not an ac tech, but here is what the manual says the error is caused by: • Thermostat did not find an indoor unit. Make sure there is a Comfort Sync® indoor unit on the system. Check R, i+, i- and C connections. • Ohm wires and cycle power. • Replace indoor unit control if there is no response.

[@warrenevans9545]

Thanks!

[@Sudz28]

Mine is completely 'off', totally dark, no white, no color, as if it has no power whatsoever. But by going to the website and checking it, it seems to be functional and working as expected. I assume this just means that the screen itself is having a problem. I hate that I can't just buy a replacement 'face' to pop on there and keep going. Never again, Lennox!!!!

[@stevenbarta1152]

Do you know where to buy the replacement screen?

[@TheGizmoGarage]

You may find some used ones on eBay or even facebook marketplace, but I recommend just upgrade to the newest version to avoid further trouble.

[@alexcruz5117]

My screen is completely white? do you think replacing the screen is worth it..

[@TheGizmoGarage]

My best guess is that if the screen is white, it's the circuit board not the screen so I wouldn't bother

[@alexcruz5117]

@@TheGizmoGarage update.. my screen went from being completely white. but still able to control it wifi on the app. Today, its unresponsive(black screen) and I am unable to control it via the app because it saids it has no wifi connection..

[@NurseNanna1]

Our initial one is completely white and that kind of money to replace it is out of our reach. Has anyone initiated a lawsuit or a recall related to this issue?

[@TheGizmoGarage]

I think people are already moved on and forcefully being upgraded to S30/S40.

[@jkeartieco]

Was your issue a white screen?

[@TheGizmoGarage]

Yes, it was a white screen

[@bm100456]

Instead of prying with a screw driver, you can just squeeze it loose with hands.

[@gurutimes2]

just buy a nest thermostat