Honeywell RTH9585WFchat_bubble_outlineFrom real comments

Many users discovered their old systems lacked a C-wire, requiring them to fish new wiring, dig into the furnace for a hidden wire, or purchase a separate C-wire adapter. One adapter reportedly doesn't work with heat-only systems, limiting its usefulness.

@raincadeify

I'm confused about the C wire. The documentation said it was for powerup the unit, but why doesn't the red power wire do that? I thought the C wire was the blue one. I'm replacing a nest which doesn't use a C wire. Apparently the colors are variable. I'm in a 50's ranch and the wires have cloth insulation that is striped white/color, if that makes a difference in why I'm confused. The HVAC company came out and wanted to replace the whole furnace (it's 25 yo so that's not crazy) but I think it's because the nest battery died. It's been there for 13 years and we've had no trouble till recently.launch

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November 29, 2025

@DaneWashingtonddtke

You are so right. I bought this device and found out I needed the C wire adapter. So we had to Google the C wire adapter for this smart device to worklaunch

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November 8, 2025

@AlanShadduck

If no C-wire connected to an older thermostat, look closely at your current installation -- it MAY be hidden/unused with the older system (tucked back into the wall or cut short at the insulated wire bundle). Preparing to re-wire mine (from 4 to 5 wire) I opened my furnace panel to find there IS an unused C-wire in the cable. Inside the furnace I simply connected it to the C terminal (after checking the wiring diagram with the furnace installation package). On the thermostat end, I found the unused blue C-wire cut short, hidden in the insulation sheath. With plenty of extra wiring tucked into the wall, I was easily able to re-strip the full 5-wire set to equal lengths to connect to the new thermostat.launch

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January 23, 2025

@CACOS-ALIVE

My wiring has the “C wire” in place. I’m buying it for boiler (heat). I don’t have a “yellow wire” (A/C). Question: It should work fine with 4wires (R/W/G/B). Right? Thank you so much!launch

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December 8, 2024

Users with 6-8 wires, jumpers between RH and RC, or unusual colors like orange, brown, or blue struggled to map their old wiring to the new thermostat's terminals, sometimes leading to malfunctioning heat or cooling.

@alienoftheapocalypse2183

I have a furnace and a my ac. Separate on my fuse box.\nMy orignal honeywell had it as :\nB blue\nG green\nY yellow\nW white\nR red\n\nWhen i set up the wires on the new one i get no power to the screen yet the furnace kicks on (blowing air no heat).\nWhat the hell am i doing wrong😂launch

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August 20, 2025

@chert023

I need help. I just installed this and my old thermostat had the R with a jumper to RC. I plugged the new one up with everything in the same location even the R in the R location. After everything was done and set up I turned power on everything worked but when I turned the A/C also known as Cool the heater came on. Any help on why the heater keeps coming on when I have it on cool? I have 5 wires G,W,C,R,Y. They were all connected to the same spots as my old one. I’m thinking maybe it has to do with the R? I’m electric as well please anyone helplaunch

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May 29, 2023

@haroldmitchell4241

The heat setting just blow with no heat. I have brown blue white green yellow red black orange. I hooked up like urs still no heat. Brown is c. Blue and black is not hooked. I had black hooked and it seem to kick out my fan and blown my compressorlaunch

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October 19, 2022

@latonyaflores101

Can i asked, you never mentioned if you had use the jumper wires for the units that have the rh and rc jumped together, is it necessary in order for the unit to work as before??launch

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July 1, 2022

Some users reported the fan running continuously even after a factory reset, and another noted the fan only stops in automatic mode but not in scheduled mode, raising concerns about electric bills.

@fmbbeachbum8163

This thing won't shut off fan in schedule mode, only automatic mode. Any ideas why. I set it to automatic & 12 hours later it goes to schedule mode.😢launch

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March 4, 2025

@gemmimms7846

Mine was great for 6 months. Then it went off for a minute and went back on. After that, the fan wouldn't go off. Even tho i reset to factory settings and then turned off completely - fan is still running. Hate to see my electric bill.launch

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March 16, 2023

Several users reported losing WiFi connection after weeks or months of normal use, with some unable to reconnect to their router despite other devices working fine.

@robjs76

Hi great video. I've had this thermostat for several years. And not to long ago I lost connection, now that I'm trying to reconnect to my router, it won't connect. What's the trick? Thanks for your help.launch

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October 5, 2025

@webcrawler3332

Has anyone had a problem with the t stat losing internet connection? Mine had been connected for a month or two, last week it won’t connect to Wi-Fi. I hotspot my phone and it connects. All my other Wi-Fi devices at connected and nothing has changed on the Wi-Filaunch

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July 23, 2022

Users reported the thermostat's clock changing incorrectly after WiFi connection, and difficulty finding the menu option to manually fix the day or time.

@cindywarner7945

The day of the week is incorrect. I do not have the selection to change day and time. It is connected to wifi. How do I change the day? The time changed automatically with day light savings.launch

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November 2, 2025

@deadlybsl485

I just installed this product. When I enter the date and time, it's correct, but when connecting the wifi, it changes the time and moves the hour back, so it doesn't observe my \"daylight savings time\" correctly. Any ideas would greatly be appreciated. Thank you in advance.launch

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July 17, 2025

At least one user reported the screen waking from sleep but the touch controls becoming completely unresponsive, and a factory reset did not resolve the issue.

@LatinPercussionist

I have this thermostat and the problem i have is the screen turns on from sleep to on but the touch is not responding its frozen unresponsive. I pulled out the thermostat for over a min reset iand nothing no luck.launch

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June 13, 2025

One long-term user found that advanced settings menus vanished after initial setup on newer units, preventing changes if the HVAC system later changed, with no clear way to factory reset.

@chorisonoma5229

So after a period of time my Honeywell Home RTH9585WF1004s removed all of the menu selections except for those needed to operate at the settings that were initially done. So there is no ability to go to advanced settings because that's no longer a menu selection. I have had this happen on the newer ones I purchased in the past year. My older units still have all the menu selections. So is this a feature or just a way of making a brick out of the thermostat if your system changes and you need to go back into the settings that are no longer there? I was looking for a way to do a factory reset that didn't depend on the menu system.launch

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February 26, 2025