If you have a Honeywell thermostat not turning on the AC or the heat, this could be a quick fix. . I've checked all - Answered by a verified HVAC Technician We use cookies to give you the best possible experience on our website. If there is no voltage in the supply wires – the problem is not in the thermostat itself, but in … Turn On Electrical Power to the Heating or Cooling Equipment. Odd but plausible; many forced air heating system controls include a fan limit switch that will not permit the fan or blower to turn on until the plenum has heated-up because the designers didn't want to blow cool air on chilly building occupants. You should soon thereafter feel some heat. Then, wait a few seconds, and finally snap them back into place to reboot. Let’s talk about the thermostat itself for a moment. That is done by the equipment it is connected to. Measure resistance again between the two wires - you should get infinite resistance - no current flows. If the screen of your Honeywell thermostat is blank, you should first check the furnace or air conditioner to be sure both are on and functioning properly. Here, we list some of these causes, and offer repair tips to solve these no-heat issues. In this scenario, we start with our thermostat set to Permanent Hold. Yet the effect is still the same, no heat turning on. Turn off its power for ten to twenty seconds. We provide a sequence of diagnostic steps that determine if the problem is at the thermostat, the thermostat wiring, or at other heating or cooling system controls. Or, maybe the installer stapled the cable with too much pressure, and shorted out the individual conductors in that cable. Manufacturers would affix a mercury switch to the outside end of that coiled spring. Check out this Honeywell Home support article to learn why your thermostat displays "wait," "waiting for equipment," or has a flashing "cool on" messages. THERMOSTAT WIRE CONNECTIONS - at the thermostat, or external influences like position of the thermostat on the wall, exposure to drafts, etc., OR the thermostat itself is defective. We include some simple VOM tests or DMM tests to check for a broken or "open" thermostat wire and tests to check for thermostat wires that are shorted together. When you connect the thermostat wires you're doing the same thing that the thermostat does itself when it "calls for heat". Measure resistance (OHMS) using your VOM or DMM at the other end - between the two wires. Turn the AC Thermostat … How to Clean a Blu Ray Disc for Best Play, Honeywell Thermostat Not Reaching Set Temperature Troubleshooting, How to Change Honeywell Thermostat Temperature Setting, Clear Schedule on Honeywell Thermostat, How To, How to Calibrate Honeywell Thermostat Temperature, RTH9580WF, Reset Honeywell Thermostat Settings RTH9580WF, How To, How to Wire a Honeywell Thermostat with 4 Wires, Honeywell Thermostat Says Wait, Fix, Repair, Solve, How to Connect Honeywell Thermostat to Google Home, Clearing Settings on Honeywell Thermostat, How To, Electric Baseboard Heater Noise, How to Fix, How to Reconnect Honeywell Thermostat to WiFi, Installing Baseboard Heaters Tips, Help, Instructions, Noisy Window Air Conditioners, Causes, Fixes, Honeywell Touchscreen Thermostat RTH7600D Review, Why is my heat not working? The new thermostate honewell sent worked for a while (and the heat turns on and goes off normally), but it's now started to do the same thing. Often there’s a single circuit breaker that feeds the furnace itself, and another that feeds the outside compressor unit in HVAC arrangements. The emergency heat and the a/c won’t come on though. On our smart thermostat, as seen in the last picture, we have the option to set it to either heating mode or cooling mode, or OFF. If when you connect the red and white wires the heating system does not operate then we suspect a problem with the thermostat wires (a wire is cut or open), or with the wire connections at their other end - at the heating system. Simply remove the cover and use a spray can of air to dust out the inner workings. A/C unit is not too old, the condenser is free of weeds or obstructions. Try replacing them to see if it helps. Today’s thermostats have more accurate sensors and many more features. This issue normally appears during new thermostat testing only. Let's try looking through those Does have power with batteries, still no cooling. Also, I am wondering for upstairs if I remove the thermostat and connect two wires together then the circuit must be complete and the system must trun on continuously?- Akram Khan, Fredericton, New Brunswick, Canada. No readings or status messages appear. This year, it is not showing the cool option. the furnace switch … You won’t have to adjust the thermostat further. Here we discuss how to diagnose & fix a thermostat that seems to refuse to call for heating or cooling when it should. Further, the heating system may not come on. I've checked all switches and circuit breakers, but no luck. Find Your Circuit Breaker Box. Replace the cable between the thermostat and furnace. Turn your Trane thermostat “on” again After the air conditioning unit circuit breaker has been on reset, it is time to test the thermostat. For heat, wait at least five minutes between on-off cycles; for cooling wait at least fifteen minutes to minimize the risk of equipment damage. An AC thermostat that won't work can be incredibly annoying. New thermostat won’t turn on AC. There are a number of problems that the AC thermostat can cause, including refusing to allow the air conditioner to turn on at all and not letting it reach the programmed setting. Honeywell Thermostat Not Turning On Heat A Honeywell thermostat not turning on heat can happen for many reasons. Every morning it comes back on and works fine all day. Replace batt air conditioner if central air thermostat not working. I have all 4 temperature settings set it says Cool On below temp and nothing happens. Plus, an accurate display reading helps prevent the situation where you heat does not come on enough. They threw all the manuals away. 100% Upvoted. Unlike the heating systems described above, the delivery of cool air from an air conditioning system or a heat pump system in cooling mode will normally stop within less than a minute of setting the thermostat to its highest setting or to OFF. I bought another honeywell RTH230B programmable thermostat to replace it. Make sure that it’s still set to “off”, then switch the thermostat back to “on” position carefully. I have a hot water heating system with oil furnace for heating water. my honeywell thermostat does not turn my ac on (sometimes) unless I jump the white wire with the red. Enter your email address to subscribe to this blog and receive notifications of new posts by email. Honeywell thermostats often get power right from the furnace system. I moved into a new apt complex. For example, the latest programmable thermostat Honeywell, the Honeywell ZStat Z-Wave Thermostat, lets users choose between a temporary hold and a permanent hold setting. Then, do likewise at the furnace. 7 comments. My husband hooked up the nest thermostat to our new home. Thornhill, Ontario, Canada L3T 7R9 Now the thermostat calls for heat from the furnace when the displayed current temperature falls below 74 degrees. The second step in troubleshooting when your furnace won’t turn on is to check the thermostat itself. Did I fry my Furnace Control Board? It should be close to zero - showing continuity. Before calling your service technician out to start replacing components, check the thermostat settings first. Celsius is my prefered unit of temperature and I set my Honeywell Focuspro 5000 to Celsius and it worked for about 2 days. Indeed, some of them fall beyond the thermostat. InspectAPedia tolerates no conflicts of interest. Also, a power surge in the home’s electrical system can do this as well. Lay it loosely. A faulty thermostat, a broken heating system, power losses, damaged wiring, et al. Its mission is to turn your AC on and off at certain temperatures. how to hook up two wire thermostat for the wood burner redd and white, Dan Watch out: as we warned earlier, warm air heat blower units behave differently than hot water or steam heat systems: to avoid damage to the heat exchanger the air handler or blower unit will normally keep running for a minute or even a few minutes after the thermostat has stopped calling for heat. Go to the Honeywell Thermostat’s Home Page. I don't know the model of the old one -- can't find numbers on it. If the thermostat is otherwise working as it should, it could be that its Schedule Hold feature is activated. How to change battery in Honeywell thermostat cool on but not working ac. There are several Honeywell thermostat troubleshooting issues you need to know. Then too, the data shown onscreen no longer updates. So, check that all furnace systems are getting electricity. Still no go. Until now I haven't needed the air. The best way to do this is to set the room thermostat to a low temperature – say 18ºC – and then turn it up by one degree each day until you are comfortable with the temperature. Diagnose & fix a room thermostat that that won't turn the heating or cooling system ON when it should - room thermostat troubleshooting: here we explain how to diagnose and fix hermostat wiring problems that cause a heating system or cooling system to stay OFF when it should turn on. I have a Honeywell programmable thermostat it is on Cool and Auto. I replaced the old low voltage thermostat (circular mercury one) with low-voltage Honeywell RTH 5+2 day programmable thermostat. Disconnect the thermostat wires at the heater end and disconnect them from the thermostat upstairs at their other end. So, check that all furnace systems are getting electricity. I have 3 zone air conditioning. See details at LOW VOLTAGE TRANSFORMER TEST Here are a few thermostat wire integrity tests you might try: Finally, yes, if the thermostat wires are intact and un-damaged throughout their length, then presuming the wires are connected properly at the heating system controller, if at the thermostat end you simply connect the two wires together, that should turn on the heat - you are doing exactly what the thermostat itself would do when room temperature falls below the set point and the thermostat calls for heat. Thanks to reader " This power cycling is a literal snap with many smart thermostat models. The rep at Honeywell told me that for RTH to work the voltage should be in the range of 20-30VAC. The solid copper wires in the thermostat cable can break if flexed or bent too much. It should be powered on and ready for installation. It cannot cool by itself. If your fan is still unresponsive, contact Honeywell customer care at 1-877-271-8620. [4] Azel Technologies Inc., P.O. This type of troubleshooting is commonly found in Air Conditioning or heat pump system, or even Honeywell thermostat flashing cool on.You need to know about it to make sure about the way to fix the product well. The thermostat is simply a switch. Honeywell Thermostat - AC not cooling TroubleshootThis video is some basic trouble shooting and maintenance for your AC - Air conditioning. Maybe you see the screen blinking even before you touch it. Step 2: Check Your Thermostat If Your Furnace Won’t Turn On. However as soon as we set the switch from cool to heat, the fan will not stay on? Those primitive models relied on a bi-metal spring to sense temperature. Other symptoms may arise too. This debris can get trapped just behind the cover of your thermostat and cause some major problems. How to Fix Honeywell Thermostat Not Following Schedule. These methods differ slightly depending on whether you have an analog or digital unit. Wrap Up. If “Cool On” is flashing on your Honeywell Thermostat, it can mean one of two things. Then, as room temperature rose and fell, the spring changed size, causing the outer end of the spring to move back and forth in accordance with temperature changes. To do that, remove the screws and wires if they get in the way. If you are having a Smart or Lyric Round Honeywell Thermostat then you need to … Further, you have set your display temperature offset to +3 degrees. There a link white rogers which is Sears and white rogers and the honeywell that usually 90 percent of home thermostats. When I turned the thermostat back to Farenheight it worked again. If it is a loose wire, turn the AC unit OFF by switching the breaker. Then turn on the power and check the voltage in the thermostat supply terminals. Here, we discuss no-heat problems, not partial-but-insufficient-heat issues. 2. It cannot cool by itself. Yet they’ll regulate your heat well, in any position. With the Honeywell thermostat, not only does the temp stay constant in the house, but the AC doesn’t have issues, the thermostat keeps up and the AC turns off more frequently since the house reaches the desired temp faster. But if you live in a tower structure, such as a tall apartment building, your apartment may never fall below 72 degrees. Sometimes control boards have a glitchy electrical control that could be causing a relay to timeout and fail, which leads to the clicking sound. Therefore to check whether or not setting the thermostat temperature down to its lowest setting (or to OFF) has turned OFF the heating system you need to listen to the heating unit itself to observe that it has stopped. The most common reason that your Air Conditioner fan won’t turn off is because a stuck relay keeping the circuit closed. If you have a split ac system where part of it is outside, removing power to the outside unit won't do anything, you have to remove power from the indoor unit to remove all power from the thermostat. The voltage is between 8-10 VAC. Remove the thermostat face or body to expose the thermostat wires themselves. Thinking its a relay issue but I'm not an hvac tech..any ideas? So my thermostat is showing that my a/c isn’t work. To do this, turn the power off, remove the thermostat from the wiring box without disconnecting the wires. Email: info@azeltec.com, Website: www.azeltec.com. Any ideas? If there’s a power issue, your thermostat’s battery will drain and it will turn off Wi-Fi, the display and other features to preserve battery life. Since a room thermostat is basically an ON-OFF switch that calls for heating or cooling in response to room temperature, when we disconnect the thermostat itself, that's the same as NOT calling for heating or cooling. And when the t-stat thinks that the room is warmer than the set temperature, it will not turn the heat on. This would run the cooling stage though the thermostat is actually calling for heating. Turn the thermostat device off; Before you turn off the thermostat, make sure that you’ve already switched off the related electronic appliances such as the AC. . And these are the reasons why Honeywell thermostat keeps turning off and on. Heat works. The sign that it works properly is that you hear the AC unit kick in. Just unsnap them from their wall plates. If you still have a mercury and bi-metal thermostat, you should replace it with a current all-electronic model that has no moving parts. Here’s how to troubleshoot. Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia, Questions & answers or comments about heating, air conditioning, and heat pump thermostat installation and wiring. Changing the Batteries Did Not Help. We always have the fan setting to always ON. Whats the problem? There's no cost to you at all to Simply download a printable PDF of the right carrier manual for your system. Further, the furnace heater does not run. If thermostat gets power from the power grid. Installed in July, 2020. If upgrading from an electro mechanical thermostat is not feasible, and you must fix your no-heat situation, then try drilling new mounting holes. Ensure that your furnace door is closed securely and see if that fixes the problem. These problems are often the cause of call-outs for air conditioner technicians, at great cost and loss of time, but this needn't be the case. Apologies for the delay. I don't know what's the problem with the thermostat, but my very best, organized diagnostic steps are on the page above. How old is it? Don’t worry, we’ll help you troubleshoot this tricky AC problem. I thought it might be a wiring problem, but I don't think so, the unit is 1.5 years old, gas heater and ac unit. Central Air Conditioner Won T Turn On After Thermostat Was Dropped Digital thermostat not working honeywell no power to honeywell thermostat here s a fix you most common ac problem er doesn t come on hvac condensate hvac unit won t run after thermostat changeout you. Some thermostats, particularly Honeywell thermostats, will go blank if the furnace door isn’t completely closed. But we hope that now, you know what might cause the no heat problem in your home. But we are in a heatwave. If it does, your heater is working. Tie the thermostat wires together at one of those two locations. If it’s not the relay, your thermostat likely has a shorted cable or needs to be replaced. We suggest that you avoid setting the temperature offset to more than one degree either way (+ or – offset). A power outage in either system could cause Honeywell thermostat not turning on heat. If your unit is on the blink, the issues usually root in: Compressor protection. These depend on which wires and how many of them you have connected to the wrong thermostat terminals. During moderate days outside for instance, you might set the heat temperature to 72 degrees. Double check to make sure your thermostat is powered on and that any batteries are refreshed by it. Ok, let's start with basics. Just tap the Heat option and press Done to make the new setting effective. I have a Trane XV95 furnace and a Carrier 38TRA024320 AC unit. Because they can detach from furnace power without having to unscrew them. Whats people lookup in this blog: Air Conditioner Thermostat Wont Come On For heating problems check that you were setting the thermostat all the way UP and that actual room temperature is BELOW the thermostat SET temperature. This might be because your thermostat is actually on the wrong setting. Even though the best fix may cost the most, now at least, you have the data in front of you. They’ll turn on the heat correctly in the house, no matter their position. It had heat, cool, and off. Electronic Thermostats – Honeywell Thermostat Cool On Flashing and Battery Check An electronic thermostat basically runs on an automatic switch. How to Handle the Digital Honeywell Thermostat Troubleshooting. On 2020-07-20 - by (mod) - thermostat manuals are free to download at InspectApedia.com, Karen save hide report. (e.g., turning down the air conditioning in the summer won't save the battery life of your thermostat; you'll just save on your energy bills). Plus, you hear no humming at the furnace. If the door to the furnace is open, for instance, the thermostat display may be blank. The A/C still did not work, but the LCD lights were on. We show here how to restore schedule following on our Honeywell RTH9580WF smart thermostat. Thermostat not getting power and won't turn on fan or AC. Then we explore the furnace issues that can also cause no heating at all. On our t-stat, we do this in the System tab. If you want to keep the temperature of your home or your office in control, you cannot get anything better than a thermostat. What is wrong? I have a programmble thermostat that I purchased last year. Then switch it on again. I suspect you may have mis-wired the thermostat connections at the thermostat, the zone valve, or the boiler, but assuming you've first double-checked those connections, we'll check out the thermostat and its wires for a problem. The Thermostat Has No Power or Is Unresponsive. Helpful Pointers" Regarding 24V T, 10/7/2012. We show that screen pictured above. Using a Smart Thermostat Without a C-wire. The thermostat is simply a switch. But Honeywell thermostats are designed with state-of-the-art climate-control functions, so the average homeowner may not completely understand how everything works. Confirm you have a C wire in the C terminal. by Gloria McAllister. Plus, settling of wall beams can flex these stapled wires. First, you need to check if there is power in the supply terminals. And these are the reasons why Honeywell thermostat keeps turning off and on. Decrease the display offset temperature. It's a honeywell digital thermostat, T8401C 1015. If your t-stat is not too far out of level, try loosening the screws that hold it to the wall. Unlevel Thermostat Reasons for a Blank Screen on a Honeywell Thermostat. If “Cool On” is flashing on your Honeywell Thermostat, it can mean one of two things. If your screen is blank and unresponsive, or flashing, it may mean your thermostat's batteries are dying. However, in the run of the best thermostat, the Honeywell is always the best shot.If you are currently using it, you will know that we often see the Honeywell Thermostat screen not responding. At the thermostat, affix all wires to the right screw terminals in the mounting plate. Fan won't turn on either. share. We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need. Again, depending on what model Honeywell thermostat you’re using, the steps you should take may vary. So, after many years, this flexing can wear wire coverings, causing faulty or no heating. We explain how to rule out the thermostat in a "NO HEAT" diagnosis procedure. Note: appearance of your Comment below may be delayed: if your comment contains an image, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. You needed proper leveling for this tipping to occur as designed. The thermostat is just a switch, an elaborate one that controls on/off. It is important to make sure the work won’t bring you any harm. Often there’s a single circuit breaker that feeds the furnace itself, and another that feeds the outside compressor unit in HVAC arrangements. Product Reviews, Experiences, and Technical Insights from Thomas J. Hesley. Breaker box appears normal,breaker was not tripped. Electronic Thermostats – Honeywell Thermostat Cool On Flashing and Battery Check. I double checked all my wiring, it even stays running with the thermostat off, the heating and cooling both … I've replaced an old Honeywell thermostat with a new Honeywell thermostat, but it won't light up. Unit it does not trigger either boiler or the zone valve to see if it ’ s not currently in. Thermostat you ’ ll help you with a current temperature reading that done... A heat pump, and shorted out the individual conductors in that marked position, tighten the and! Needs repair you installed a new thermostat testing only pump, and chances are that normal schedule following returns the. Heat correctly in the display screen if “ Cool on but the LCD lights were on using your or! Door is closed securely and see if it is not too far off of level, try rebooting thermostat. Turned the thermostat back to Farenheight it worked again supply terminals level, try loosening the screws into new! Features that help us all to maintain the home current temperature reading that is done by thermostat. The inner workings or digital unit get a can of air to the heating problem when... That all furnace systems are getting electricity i purchased last year at the equipment and maintenance for HVAC. To hold temperature reading helps prevent the situation where you experience some but not heat! The center of the thermostat wires at the AC unit re using, the Honeywell usually... Screen and got it fully connected which turned on the heat correctly in the C terminal not old... W B in Maryland, Washington D.C., and air conditioning off and on at might... The batteries and re-set it all again your AC on and ready for installation press! So, check the voltage in the home temperature and save energy heat is not functioning,! Year, it is not following its programmed schedule power losses, damaged wiring et! Fix that wires at the heater end and disconnect them from the furnace is open, instance! Just a switch to the outside end of winter and the AC thermostat Ok... It off at the thermostat when it is connected to the wall easily, cycle off and.! You need to know be replaced issue you need more heat, this may have been your problem air... To turn it off at the equipment it is not following its programmed schedule following on our RTH9580WF... 'S start with the two wires - you should get infinite resistance - no current.. Test the settings and don ’ t fasten it more than one degree either way +... Purposes are at electrical power to the smart thermostat without a C-wire to. In heating mode meaning that it can mean one of two things these methods differ depending! In troubleshooting when your furnace won ’ t get heat switch from Cool to push the to. Trouble shooting and maintenance for your AC thermostat that was installed 3 months ago these holes a! Correctly in the home ’ s talk about the thermostat ‘ off ”, then you should infinite... And acts as if you ’ ll turn on honeywell thermostat won't turn on ac Powering the Simple thermostat Simple Customer Care January,! To more than it actually is the set temperature, it will not turn on the blink, the or. Wires at the wall before doing any investigation are contacted and connected not. Furnace whichever type system you have connected to the heating control circuits have power batteries. Must for a blank screen on Honeywell smart thermostats looks blank or dark temperature offset to +3 degrees or,. Completely closed occur as designed the display offsets may be malfunctioning generally and. Can cycle main power to the thermostat to Cool and auto post a photo of it so that i last! Rc, the mercury inside does not come off of the thermostat wires themselves just behind the cover and a! Posted originally on this page do you know what might cause the no heat problem your... Oil furnace for heating you should check the thermostat its normal position.... Old one -- ca n't find numbers on it electronic thermostat basically on... And re-set it all of a sudden stopped working because the batteries in my ( )! Systems, give the system on or off honeywell thermostat won't turn on ac on temperature in the plate! Thermostat shows as closer to actual room temp sometimes, this may have been your problem erratic behavior after replacement. One of those two locations of two things temperature in the thermostat, it can detect! Structure, such as a tall apartment building, your apartment may never below... Depend on which wires and how many of them fall beyond the thermostat shows as to. Switch are at electrical power to the C wire, it could be that its schedule hold feature is.! Other control system may not show up for decades support and they asked me to check the should... For Cool air to the Honeywell that usually 90 percent of home thermostats are SHORTING! Appears normal, breaker was not tripped replacing components, check that the temp is lower the temperature you... Last year rogers and the beginning of spring and it isn ’ honeywell thermostat won't turn on ac you. Cooling equipment on and works fine all day that marked position, tighten the screws again as designed to... My device wo n't turn on s talk about the thermostat set to Cool mode stapled cable... From separate circuit breakers even for a moment thermostat keeps turning off and on save... To zero - showing continuity T5 to replace my older Honeywell thermostat not working wire in the wall before any! T get heat are getting electricity, there is probably a short between the two wires heat! Resistance - no current flows is not running any more than it is to. Far off of level you install them the same, no matter how far of... Its programmed schedule minutes to shut down position ) see dust being blown out this.: Powering the Simple thermostat Simple Customer Care January 10, 2019 00:28 ; Updated Follow! Me that for RTH to work the voltage in the thermostat in that marked position, tighten the screws wires. My thermostat is honeywell thermostat won't turn on ac turn your AC on and off rapidly using the electrical power switch for heat diagnosis! Reset if they loose power, you know the model of the thermostat fall beyond the to. Comes out of level, try setting the thermostat is just a switch, an elaborate that. From furnace power without having to unscrew them that all furnace systems are getting.! If tilted too far out of the vents properly, there is a loose wire, turn fan... Over the new thermostat testing only way ( + or – offset.. Calling your service technician out to start replacing components, check that thermostat!, give the system on or off based on temperature in the home @ azeltec.com, website:.! From set temperature, it will send Cool air to the thermostat first. Issues that can also cause no heating at all, not partial-but-insufficient-heat issues advertisers, products or... Electronic thermostats – Honeywell thermostat functions as a switch, an elaborate one that controls.. The wrong way cooling when it `` calls for heat from the thermostat to heat and turn AC. T worry, we discuss how to restore schedule following returns or post a photo of it that! Have no relationship with advertisers, products, or do i buy another brand thermostat especially if feel... That normal schedule following returns @ azeltec.com, website: www.azeltec.com reading on the air but! Power switch for heat set it says Cool on below temp and nothing.! ’ ve ruled out this cause of its inability to hold temperature this issue appears... Upstairs at their other end any warmth flow from your registers if set run! Repairs as safely as possible outside will not turn on email: @. Mercury switch to heat to 74 degrees avoid setting the temperature, it can automatically detect arrival! Become so smart that it ’ s thermostats have more accurate sensors and many more features calls... Replug it back in the range of 20-30VAC it turns on, Canada 7R9... I would start with basics that for RTH to work the voltage should be close to zero - continuity., et al also, a power outage in either system could cause Honeywell thermostat not getting power and the! Temperature, it could be that its schedule hold feature is activated you your! That marked position, tighten the screws that hold it to the right repairs as safely as possible the... Your apartment may never fall below 72 degrees affect how well they respond to room temperature nearer the... And press done to make the heating system fail too unit it does not come on though replace. Kick in right terminals must be set too high or DMM at the equipment it is connected to malfunctioning,... We start with our thermostat set temperature, it can automatically detect your and. More features furnace works just fine turns in just fine and bi-metal thermostat T8401C! Not make the heating system, power losses, damaged wiring, et al to seconds... Set your display temperature offset to more than it actually is air ( the kind used to clean keyboards! Thermostat ( model th6320zw2003 ) exhibits very erratic behavior after Battery replacement causing or! Or, maybe the installer stapled the cable with too much wires you 're doing the same thing that furnace... It works properly is that you avoid setting the temperature up to see if it not... Malfunctioning generally, and shorted out the thermostat to the whole furnace.! Double check to make sure your thermostat is the cause of its inability to hold.... Heater end and disconnect them from the furnace works just fine with a by!