A thermostat is one of those things that you don’t pay too much attention to until it breaks. Usually, thermostats do their job quietly, in the background, without requiring much outside interference, but when it stops working, everybody in the house notices.
When the temperature inside is suddenly freezing cold or burning hot, most homeowners will do just about anything to fix it and restore a comfortable environment. Before you call the repair man to fix your air conditioning or heating unit, make sure the thermostat isn’t the problem. Below, we outline some things you can do to check its functionality and ensure you have a working thermostat. Before anything, you need to determine which type of device you have and understand how it works.
Electromechanical thermostat devices are older and more basic than modern examples, operating on very simple mechanical principles.
A strip of two different metals joined together rests just under the cover, sometimes in the shape of a coil. This strip, or coil, will expand and contract with the fluctuating temperatures, activating the contacts on either one or both sides of the metal. If the unit controls the heating and cooling functions, it will have contacts on both sides; if it only controls one option, it will only have a contact on one side.
In a dual-controlled unit, this switch will tilt one direction if it is hot and the other if it is cold, creating contact with the appropriate side to activate the heater or the cooler to turn on. This system is sometimes joined with a mercury switch, which is a tube filled with mercury that also tilts as the coil expands or contracts, causing the mercury to move from one side to the other and thus opening or closing the points of contact.
Modern types of thermostats are electronic and function like a small computer. Often times these are programmable, allowing you versatile flexibility in how you set temperature controls, timers and preferences.
Unlike electromechanical thermostats, which require manual adjustments, electronic versions allow you to set the temperature for a different setting when you sleep, wake up, return home and even for different days, such as on weekdays and weekends. This is a much more convenient setup than the simpler models, but it also means that there are more pieces that can break and maintenance work is more difficult and expensive. There are often inexpensive electronic models, making it often more feasible to simply replace your unit than try to fix it.
Now that you can assess which type of thermostat you have, it will be easier to determine the problem. While some fixes require a trained repairman, there are several issues that you can resolve on your own. Here are some common problems and solutions that you may find helpful:
Being caught in the cold winter months with a faulty furnace is a situation that nobody wants to be in, but there are things you can do to remedy the problem on your own. Here are some suggestions to try if your furnace won’t turn on:
While performing these simple fixes may not correct the problem, they can help you narrow down the issue to make it easier for the repair mechanic to quickly determine the problem and cause.
Another function to check before calling a professional is whether the thermostat keeps the room at the correct temperature or not.
To do this, tape a small thermometer on the wall next to the thermostat, being sure to place a paper towel behind the thermometer so that it won’t be affected by heat or cold transfer from the wall. Wait for at least 15 minutes to ensure that temperature is stabilized and giving a correct reading, then compare it to the reading on your thermostat.
If the numbers are more than a degree apart, the thermostat is likely not giving an accurate reading. This is a very important factor to know when you speak with the repairman about the problem.
Some other factors that you should take note of when diagnosing your malfunctioning thermostat are listed here:
Having a furnace or cooler that won’t turn on can be frustrating, but finding that yours won’t turn off can be equally difficult. Try these simple fixes to get your unit functioning properly again:
Having a thermostat that functions correctly is vital to keeping your interiors comfortable and livable during any weather. Many of the problems require simple fixes and can sometimes be taken care of on your own, but more complicated issues will need the help of a mechanic or even require replacement. After taking a look at the problems and solutions listed here, you should be able to determine the difficulty of your issue and whether or not you’ll need a professional.
An avid jogger with a knack for solving crosswords, Karen is a culinary chef taking a break from the long hours of her catering business to raise her two boys. Aside from baking the best double-chocolate brownies you've ever tasted, she currently spends her free time writing about the joys of cooking and reviewing a variety of appliances you may find in the kitchen.
I can’t change the settings on my new Emerson thermostat. There is an icon that appears to be a lock. How do I unlock it>
If this is a programmable thermostat,
1. Open the door.
2. Press and hold the “Home and Sleep” buttons at the same time, for about 3 seconds.
3. Press the “Up” button until you see “U3-On”. If not, press the “Mode” button until you get to “U3-On”.
4. Press the “Up” button again to change it to “Off”.
5. Press the “Done” button and close the door. Consult your operators manual for your specific thermostat, or download a copy of the operators manual from the manufacturer’s website, or search for your model’s manual. You can also check your warranty registration to find the model number.
When I try to turn my thermostat up or down, the numbers (digital) start going haywire. What should I do?
The most probable cause will be either a loose wire or dust inside the thermostat.
1. Turn the thermostat ‘Off” first and remove it from the wall base. It should come off easily. Get a can of compressed air (the kind used to clean computer keyboards), and blow it out. If you see dust being blown out, this may have been your problem.
2. If it is a loose wire, turn the AC unit OFF by switching the breaker. With a screwdriver, check the wires connected to the thermostat box and tighten if necessary.
3. Turn breaker back on and set the thermostat ON. Check again if either of these issues fixed the problem. If not, you may have to call a professional for a $$$ service call, or go to your nearest home improvement store (home depot, Lowes, etc.), and just buy another thermostat that matches your unit. They are usually half or more in price than what the AC company will charge you.
Just installed a non programmable thermostat it’s 120v electric, When I turn on at 78degrees for the night, the thermostat cut On and Off throughout the Night, what setting does the thermostat need to be on to something that it won’t shut off, Auto or Heat , or could there be another problem. No furnace, it’s 120v Electric, very simple to install
My ac won’t come on I push thermostat in it cut on 30 seconds the cut of what wrong i hsve a non programmable digital thermo stat heat set at 68 but inside temp is 76 why is this ?What temperature is it 3 inches in front of the thermostat. That is the only area the thermostat can feel… it will not know 10’ away or another room that it controls for that matter.
A thermometer will only show the temperature it touches(under your tongue), think of it that way. If the thermostat is reading the same temperature as the air right in front of it- give or take a degree, but other areas of the house are too hot or too cold- than its your home heating system that needs to be balanced. If the air inches in front of the thermostat are very different (4+ degrees different) then it is your thermostat that is “out of wack”…
Also the location of the thermostat in relation to its surroundings… is it in a place where the sun from a window can shine on it?- that can cause it to misread temperature of a room.
I’ve seen people put a tv stand with a flatscreen in front of it- it gets warm behind a tv and that can heat it up prematurely. If it’s installed near a heat source, ie: baseboard, hvac duct, in/near a kitchen or boiler room… also I’ve seen where a heat line to another floor was ran inside a wall, heated up due to a call for heat upstairs and the first floor thermostat was installed right on that piece of wall and was actually being heated up from behind, causing it to not come on when turned up because it was already being heated from behind.
by the way if it is a newer (after 2010) Honeywell round, non programmable thermostat… have been having many problems with those not being calibrated properly When it comes to a thermostat- it’s location location location…
Then if you can start looking at things like *secondary heat source, the heating system being unbalanced, or the actual Tstat being defective*… and one last thing- it doesn’t matter if the “low battery” symbol on a battery powered Tstat is lit or not… if the batteries are low it won’t always just die… that can also cause a Tstat to perform erratically. Good luck.
On my thermostat it’s keep going higher when the AC is on put the AC feels like it’s working what is saying the house is getting hotter what’s the problem
when I press the up or down arrows on the thermostat, the digital display for the temperature does not move. I have the temp set to 70 degrees and it will not change whether I press the arrows up or down.
Batteries are a must to keep your Thermostat working regularly! Once a Year, change! Like anything else in our society! Use a Calendar for every important upgrade! The only way to be accurate!
BATTERIES NEED CHANGING!, YEARLY! MAKECA NOTE ON YOUR YEARLY CALENDAR! SAME DATE, DIFFERENT YEAR!Very good idea Gayle. I heard my stepfather talking about those things when I was a kid, and forgot about it. Guess my age is messing up my brain. Take care of yourself girl. And God Bless you.
I have to manually adjust our thermostat to turn the a/c and heat on or off! It will not start or stop any other way! Any ideas? I’ve been telling my hubby we need a new thermostat for, well, I’ll cut him a break and simply say for AWHILE! I just opened an electric bill for $460 for the month! The unit is only installed in about 1000 sq feet of the home!
We raised our AC to a higher setting on our thermostat for the weekend but when we returned just the fan works . None of the panel shows any temps. We changed the batteries, checked brakers, & drain pan system. Help!!
My ac unit is cooling and achieves the set temperature. After it automatically cycles off, the temperature on the thermostat rises every 5 minutes and causes the ac unit to cycle back on. What can I do about the ac coming on every 5 minutes?
My ac keeps running after it reaches the set tempature and wont turn off …i have to turn off manually nomatter what tempature is set on
My thermostat will not maintain the number it is set to. When set to 68 in the winter it continues to rise way above the setting. It does opposite during the summer. HELP.
Quality Heating and Cooling out of Wadsworth, Ohio told us we needed a new furnace( it is 45 years old). They put a temporary furnace in until next week when the big one goes in. The temp furnace is doing the same thing.
oh my, having thermostat issues and was reading some comments to try to trouble shoot and laughed when i read this one. I think that may be so that it’s warm and cozy when you come out of the shower. Your house loves you, good luck
Your hot water is likely heated by your furnace so the furnace is starting to heat the hot wayer as you use it.
Thermostat needs changedI turn on the a/c, but it did not come out cold. The inside temperature on it has read the same thing for the whole day, 83. I have the a/c set to 78, but it’s only blowing out room temp. It’s like 100 outside, and cearly its been getting hotter & hotter in here, but the temp still says 83.
Is it a bad thermostat? Would that cause it to not blow cold air? Is there anything i can do before caalling the repairman? (They’ve all got a 2-3 day wait anyway)
I’m thinking I may have a bad thermostat (it’s probably 10-15 yrs old), just not sure if that would cause it to not blow cold.
Help, please!
Thanks,
Hot in Cali
A.C. nor heat will come on. The thermostat lights are on. The temperature settings do adjust but nothing comes on. What can be done?
You need to reboot your thermostat. Simply remove it from the wall mount and take batteries out for 30 seconds. Replace batteries and go through the setup on the screen. Hope this fixes the issue.
My programmable thermostat was turned off but my house was heating up. It got to 94°, I pushed the reset button and the air came on. Should I replace the thermostat?
My thermostat says 72 and I have a set at 72 and it will not shut off it’s been running like this for at least 30 minutes
How long does it take for fan to come on, after burners heat? May have typed it wrong because I’m not a heating or A/ C person. Thanks
I have no power to my my thermostat sometimes when I do its reading 23 degrees it will run sometimes and sometimes it won’t
Got my thermostat set at 74 but it says house temperature 64 will go no higher do I have a bad thermostat it’s only 2 years old the furnace is only 2 years old too
My heater only blows heat for a couple minutes then shuts off. Then takes a long while before it turns on again. PLUS the settings on the thermostat and the actual temp are about 10°off.
I’m having same issue and high electric bills. I don’t know what to do either. I have an older intertherm thermastat
Every time I try to turn the temperature up it drops right back down to set number which is not good because my building be cold. How do i fix this problem.
Why do my thermostat make noise and don’t come onMy heat pump broke on my hvac unit.my inside furnace works. problem ; my heat pump broken.heater inside works. fan will not stop even when furnace heat has stopped
Do I have to disconnect any thermostat wires to compensate for loss. ;
Freezing temps here and my furnance is working overtime. My thermostat kick furance on, it heats up for a few seconds then kicks off sometimes. It will start back up with no problem and sometimes does the same thing again not kicking on. I kicked on a heater on our 2nd level thinking the draft was making the thermostat kick on too often since it is placed on the wall at the bottom of the stairs and seems to have help. Any idea if it would be thermostat or furnance?
the aux. heat keeps coming on and we have to drop 1 degree to kick off. and when it comes back on aux. heat kicks on . my last elec. bill last winter was 398.00 BUCKS in the winter it runs like 150 to 200 what can i do
I change the pump on my boiler .Started it at 68.i don’t hear the pump. When I set it he heat at 78 the pump push the water thru but water just keeps running and pipe just gets warm but not hot
All four electronic thermostats, to baseboard heaters, failed and gave an error code [ E1 ] when I opened the cottage last weekend. The temperature at the time was about -22C. The supplier now indicates that they will likely all have to be replaced. I am questioning replacing with the same or similar ones. Are there electronic thermostats available that are better suited to handle start-up at very cold temperatures?
Should I consider going instead with electro-mechanical thermostats to better handle extreme cold situations?
Hi,
I have water heat in my house. I set the thermostat to 71F (and hold the temperature) and the furnace to 200F (when it drops to 180F, the boiler automatically activates to go to 200F again). However, after several days the furnace drops between 140F to 110F no matter how I adjust the thermostat. The only way to bring back the temperature to 200F in the furnace is by draining the water. But while draining I cannot see any air. This happens in the course of every 3-4 days. Please advise. Thank you!
Your furnace will short cycle if your furnace filter is dirty or if the blower motor is covered with dust / grime.
My thermostat is set to 71 but the temp in the house keeps dropping and the air coming out of the vents is cold the change battery sign just came on could that be the problem and my inside unit won’t turn on ?
My thermostat is set to 73 but the temp in the house keeps dropping to 65, and the air coming out of the vents is cold, What is going on?
You might have a thermostat that has A/C, then a combo AC/heat setting and then a heat setting.. This is what I have. From my understanding you need to set these correctly. I rarely use the combo setting but if I set the heat part to high, it seems to disable the normal heat setting..So I have the A/C set at 73, the combo setting is set at 72 and the heat is set at 72. When I moved the combo setting up to 76, then my heat setting no longer would hold the temperature and dropped as low as 67 before I reset the combo setting back to 72. This is all with my boiler disabled(ignition is out, will be fixed shortly). And when the boiler goes out, you notice huge difference in temps in the basement as the concrete gets cold and it just is colder throughout the house. I may not have my settings entirely correct but when I reset the combo setting, the heat came back up to 71.
I’m having to turn my thermostat up to 90 (the highest it will go)& manually keep it on instead of auto, to heat the house or either the temperature keeps dropping again.
My thermostat is programmed for 68 degrees when heat on, it’s reading 81 , it has power , is it time to change, it’s a Honeywell CT3200 model
I called my electric co they said if aux comes up on thermostat there is something wrong with system I have my thermostat set at 74.but the heat keeps coming down to 70 and 72 ..My furnace turns on if set “on” but blows only cold air when on heat setting. If I put it on auto and set a few degrees above room temp
Thermostat clicks like its going to turn on but never does. Should I replace my thermostat??
Can you please tell me what you had to do to fix that… I habe my heat set for 73 it starts for a minute then shuts off … The house temp it has got down to 62. My heater wont stay on long enough even to blow out warm air. Does anyone know how to fix or whats wrong?
I have a whites and rodgers thermostat 1F86 – 344 and I noticed its not acting right, I set it to lets say 68, it reaches its 68 mark but before it falls below 68, the heat comes on again, isnt it suppose to come on at 67 ? What could be the problem ?
Where do you have your thermostat placed…is it away from a window or door? My thermostat reads 70 but the house is 65I have touched the low voltage wires together at the unit. The thermostat went dark on the reading panel inside house. Do I need to replace the thermostat?
Will you refrigerator make a wrong temp reading on the thermostat if it’s on the other side of the wall?
The fan turns on in the heat setting but not in the cool setting. Did we wire the thermostat incorrectly?
My thermostat is set at 71 for cooling in the morning my house is 67. What is the cause.My Central Unit was recently repaired. Twice in less than a week. It was down since Feb this year and we just got it back up and running, well the Blower Motor went out from over use, (My ex boyfriend thought he was an HVAC savvy and ran it with out a filter, etc) My fiance and I got a new display put on and we set it to 73, it was running fine til Saturday (6/02/2018) when I noticed it was turned off which is something we haven’t done. My ex boyfriend was over spending the night because he was taking our girls back home with him and only agreed to him staying per request of my girls since his birthday was coming up in a couple days.. Ever since we noticed after he left our Central unit has been reading 75-78 but has been set at 73 and has been running nonstop. We checked outside only to find out my ex ripped the weather stripping tape used to keep the cold air and hot air in (Depending on the season) We replaced the tape and the Unit cooled down to 73 again but now it’s shot up to 76 currently. Anyone know what may have been done? We can’t get the tech out here til after Wed morning. We use a Deposit based account with our lights (Meaning we pay a set about each day, in our case we pay the amount of $150 a month and they take out the money each day.) Our bill is normally $4.00-$6.00 a day. Please need help or advice!
What would cause a central air unit to shut on and off.. the inside is 91degrees a
D we have it set for 70 and the unit blows cold air for 3 mins and shuts off
We set the temperature at 75…and it changes by itself to 88… So I constantly have to be adjusting the thermostat to 75. Any suggestions why.
Last winter I left my thermostate in my apartment on OFF on my thermostate all winter long to save money. My apartment temperature got as high as 83 degrees WITHOUT MY THERMOSTAT BEING ON. When this thermostate was installed the installer told me that the therostate in my apartment controlled the heat and AC in my apartment only. He gave me the anology of staying at a hotel and the guest set the termostate in their hotel room to the temperature they want in their room. This problem didn’t occur winter before last. Help, please!
My outside AC unit will not turn on at all My furnace turns on and blow out air but not cold air. My “cool on” is flashing on the thermostat and according to the manual that means the compressor protection delay is underway. How do I know if its the thermostat or the actual unit outside.
My ac unit all ways seem to trip the breaker after running maybe an hourmy thermostat is set at 70 but the ac doesn’t kick on till temp is 74 or 75 degrees in the house, thermostat is 11-12 yrs old, ac blows fine once it turns on but it’s not turning on till 74/75, time to replace thermostat?
When I flipped the switch from cool to off, it shows that it is still on cool. Even if I switch it to heat. It keeps showing the snowflake and not the flame indicating it switched over.
I did the check I set my thermostat at 75 but the temp inside is 80 , check with a normal thermometer and the temp. In my condo is 80 degrees what causes the difference have new unit AC two years ago. Is it a thermostat problem?
They are doing roofing on my building also and was fine till this started.
I set my heat to 72. Thermostat stays on 72 constantly. It reads seventy two when it comes on and temp is also 72. Normal or have it looked at. Husband is no help!
my thermostat is set on 70 stays on70 when comes on and does not go down or up. comes back on at 70 and does not go down after furnace goes off
Hi my problem with my furnace seems to be right after summer when we stop using the ac because it’s getting colder. Our furnace will kick on and blow out cooler air but the thermostat will be set to off and the ac unit outside doesn’t come on, just the furnace inside. It will come on for a couple minutes then shut back off, and it can repeat this a couple times within an hour. Eventually if I want to stop it I have to shut off the breaker to get it to shut off. Why would it be doing this. We got a new thermostat unit last year but it didn’t solve the problem. This has been going on for over 2 years and drives me crazy. Not to mention I worry it costs electricity when it does that. I noticed it use to do it more so when we would have our ceiling fans on at night and it would get pretty cold in here and it would be 66 or 65 in here in the morning and it would start doing it. But the other day I looked at the thermostat (which was off) it said it was 70 in here and it started doing it.
My thermostat says 67 degrees in the house when the temperature reaches that it shuts down . But within 4-10 minutes the thermostat says it dropped down to 61 .. can it be dropping that fast and the thermostat kick back on ?
My thermostat is set at 71, but the heater doesn’t turn off until the thermostat reading reaches 75 or so. What is going on? Anyone….?
My furnace will not come on in the automatic position but will when you switch it to on. But it will not blow warm air.
hi, I have a simple emerson thermostat with an off or heat , up and down arrow button. The temp on the right is lower than the temp on the right. I assumed since I’m able to change it the temp on the right is what I want the temp to be at. For example: I set the heater to 72 but the house says 68 and the heat hasnt kicked on.
My furnace runs but the blower fan on the unit outside (gas pack) cuts off within 3 seconds after you cut it on. Replaced the capacitor. Didn’t solve the problem. The contactor thing is not “sucking in” to make contact. When we push in the contactor, the blower fan stays running.
This seems like such a good idea, will have to take a look at it!I came home to find my thermastat reading 85 Devrees in the house and it is set at 69 degrees. what could be wrong?
There are a number of reasons why a thermostat wouldn’t be reaching the set temperature. It could be a problem with the thermostat itself malfunctioning or the fan in your AC system is not turning on properly, preventing the temperature from lowering to your current settings. Another issue may be that the thermostat is losing power partway through the cooling process. Finally, you may be looking at a thermostat that isn’t designed to operate for the size of your house. If your thermostat is designed for use in a much smaller space, it may not be operating in a way that can meet your needs.
My thermostat is programmed at 20 celsius but it can only get up to 17. The hot water in floor heating system has been running 24/7 for 4 days during a snow storm but it won’t go pass 17. The house feels cold. Today was sunny and the storm ended last nigh and got much warmer and melted a lot of snow. the thermostats went to 21. This year I got the electric hot water tank replaced in October. we haven’t have this problem in this home since we moved in 10 years ago, even during snow storms.
It’s 50 degrees outside and my thermostat says 76 degrees but no matter what the thermostat reads I put it 2-3 degrees higher and it still won’t turn on..I have to put it on 78 in order for it to blow and it only lasts for about 2-3 minutes and it’s cold as hell in my apartment..PLEASE tell me what I can do to solve this issue
It’s always on and not blowing heat or it’s up very high and blowing too much heat which is causing my electric bill to be too high..I need help
Had a new American Standard Furnace put in Dec. 12th, with what was supposed to be a new thermostat. That is okay, if it would work right. I have a lot of dust & try running it on “Run Only”, but it will not work on anything but AUTO. Tech swears it will, but can’t get him back out here. I have it turned to off, with it set on run…no luck. Help…me pls. I have allergies something awful. thanks
its a honeywellI have a Honeywell 9000 thermostat and two-year-old brand new AC system I live in Florida and the temperature has been hot I set it to be 74° it stays at 74 all day until about 5 o’clock in the evening and then the AC is not being satisfied the inside of the house shows 76 and stays that way for 3 to 4 hours and miraculously jumps back down to 74° could someone tell me what is going on?Its been happening all week
