Honeywell ac blinking cool on

A "cool on" message can also appear if the thermostat logs out or times out on its own. Wait 5 minutes, restart your thermostat, and identify and replace fuse or wire damage to make it return to normal. Thermostats can also flash a "cool on" message if it is working hard to produce cool air. This can happen even if there isn't an ...

So, when your Honeywell thermostat is in the blinking stage, it shows Cool-On for more than 5 minutes – But there is a feeling that the surrounding area is not cooling down, there is no cool air coming through the system either; you might need to fix the problem. Down below, we will divide the troubleshooting procedures into six quick steps.2) Warning Light (when flashing) 5) Fan Speed Control 3) Mode Control 6) Timer Control Settings: Air Conditioning, Heating*, Dehumidifying, Fan. The corresponding indicator light will illuminate to indicate the current mode setting. MODE CONTROL Air Conditioning Mode Adjust fan speed and air temperature to suit your desired comfort level.Check if the thermostat is set to “Heat” mode and if the “Heat On” button is blinking. This means that a safety timer for your thermostat’s compressor has been tripped. Once this stops the heat blinking, your thermostat should be able to maintain its heat setting again. The 4-5 minute blinking is the time delay.Hello I have a Honeywell T4 Pro that was flashing "Cool On" on the right side of the screen. Nothing seems to help I did replace the batteries and it stopped blinking and now it is solid "Cool On" When I run the test it does kick the AC on. So the AC itself is fine. It seems like it is something with the thermostat. It has fresh batteries.A - Cool on blinking means the AC is currently ON and providing cool air to the house. It prevents the system from short-cycling; this message usually vanishes after 5 minutes. ... Like Nest, Honeywell and Carrier thermostats, now is the time to discuss another category of thermostats: Hunter Thermostats. These thermostats …Oct 30, 2020 ... John Franco•19K views · 3:26. Go to channel · HVAC Thermostat Blinking Cool On But A/C Not Working. Word of Advice TV•138K views · 1:47. Go to...Why is my system heating when it's set to cooling? 1. Verify the thermostat is wired correctly. 2. Make sure the thermostat is configured correctly for the heating/cooling system type. 3. Verify the wiring is connected correctly and securely to the thermostat. If the above information has been verified and the issue is still present, contact a ...The fix. If your thermostat is flashing cool on, wait for 5 minutes until the delay is over. Usually the thermostat delay should not take more than 5 minutes. However, if your thermostat is not blowing cold air after the delay period, there could be issues causing this problem. Let's go to the next step to find out more.

The blinking cool on your Honeywell thermostat indicates a potential issue with the cooling system, such as low refrigerant or a faulty compressor. Why Is My Honeywell Thermostat Showing A Blinking Cool But No Ac? If your Honeywell thermostat is showing a blinking cool but no AC, it could be due to a problem with the cooling system’s ...If your Honeywell thermostat is not working after a battery change, ensure the doors are closed because if your HVACs access doors are still open, you may still have a blank screen. If your Honeywell thermostat display light is not working even after this, it could be that the circuit breaker has tripped. The display screen should be activated ...Confirm the message "Heat On" is solid (not flashing) on the thermostat display. Confirm your wiring is correct, and the wires have good contact in the terminals (tug gently on the wires) Check your jumper wire. To operate heating, the thermostat requires power to the R terminal. (If you have a wire in the RC terminal and no wire in the R ...The Honeywell 8000 thermostat is a popular choice for homeowners looking to upgrade their heating and cooling systems. With its sleek design and advanced features, this thermostat ...During the brief wait period, the thermostat will flash Cool On (or Heat On if you have a heat pump) until the wait period is over, at which point the compressor will turn back on. Note: The flashing Cool On or Heat On message is also used for startup delay protection if AC power loss occurs. Without wishing to be too rude, many manuals for ...The red light blinking on your Honeywell portable air conditioner indicates a potential issue. It is likely that the filters need cleaning. ... How to solve an air conditioner blinking red light problem: Clean and wash the filters; ... Air conditioners are essential for cooling the air in your home and come in various brands and models. When ...If it is enabled, just press the 'disable recovery mode' option. 2. Monitor the results. Give your Honeywell thermostat around a day to see if the recovery mode turns on. Likely, this should not worry you. If that period of the day ends and the thermostat switches into recovery mode, there is something wrong. 3.Please try again. Check the name or model number of your product to ensure it's correctly written in the search bar above. If you're looking for a product that isn't a thermostat, try checking here.

If you see Honeywell thermostat flashing cool on, give it a time, around 15 to 20 minutes. Just turn everything off and wait. After the minute has passed, try to turn it on again. If nothing happens, contact the manufacturer’s customer service. But if the system works again, you know that you only need to give it time.Common Reasons for Honeywell Thermostat Blinking Cool On. System Starting Up The Honeywell cool on blinking is often seen when the system is just starting up. It’s a brief pause to ensure the compressor doesn’t cycle too quickly, usually lasting no more than 5 minutes.Feb 22, 2022 · Why is the "Cool On," "Heat On," "Snowflake," or "Flame" blinking on the thermostat display? Last updated. 2/22/22. The thermostat has a built-in 5 minute delay to protect your equipment. If “wait” is in the screen or “cool on” is flashing – wait 5 minutes for the system to safely respond. There might be two reasons in Honeywell thermostat’ blinking: 1.With a heat pump installation process, blinks are replaced with “flashing.”. If the thermostat is installed in this type of system, then compressor protection should be checked. To do so one must see if an “on” message appears when pressing either cool or warm buttons on ...Wait for at least 45 to 60 minutes to see if the cool air gets pumped out of your air conditioner. Low batteries The status of the battery in the thermostat plays a significant part in the blinking of the COOL ON indicator. If the batteries have low power, the thermostat won’t be able to detect the surrounding temperature.

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control. This feature is NOT displayed if feature 200 is set to Cool Only. 218 = Reversing Valve O/B 0 = O (O/B in Cool) 1 = B (O/B in Heat) Note: This option is only displayed if the Heat Pump configured. Select whether reversing valve O/B should energize in cool or in heat. 220 = Cool Stages / Compressor Stages (200=Conv / 200=HP) 0, 1, 2Do not worry. It’s a much more common problem than you might think. 90% of the time, it won’t be a huge problem. It’s just a ‘feature’ of the Honeywell Thermostat. The only time you need ...I have a pro 3000 Honeywell non-programmable thermostat. Everything was working fine, then we left town for a few days, and it no longer works properly. The fan and cool air will kick on but the heat … read moreWhen I turn on the thermostat to cool, the AC condenser turns on for 5 sec and turns right off. ... is there a way to reset me my honeywell dual zone unit. it is not cycling on and the purge light is blinking ... I have an AC system using a Honeywell EMM3 mini zone controller. There is an upstairs bedroom zone, and and main floor zone. ... If you see Honeywell thermostat flashing cool on, give it a time, around 15 to 20 minutes. Just turn everything off and wait. After the minute has passed, try to turn it on again. If nothing happens, contact the manufacturer’s customer service. But if the system works again, you know that you only need to give it time. A blinking “Cool On” message can indicate various causes, such as dying batteries, a power surge, or a power outage. Thermostat batteries generally last for an average of 10 months, making it easy to identify when dead batteries are responsible for the blinking message. However, sometimes a Honeywell thermostat can recuperate after a power ...

RCHT8612WF2015/U, SMHOM8610KIT, RCHT8612WF2015/W, RTH8800WF2022/U, RCHT8610WF2006/U. Download Manual Download Installation Guide. Download Service Datasheet. T5 SMART THERMOSTAT Product Page.The “Cool on” message on a Honeywell thermostat is also known as “delay mode”. It often flashes in the form of a blinking snowflake or as the word “wait’ as well. It’s a courtesy message to let you know that the AC will delay in coming on for approximately 5 minutes in order to protect your unit from short cycling which can cause ...Step 1: Check Wi-Fi Signal Strength. Weak Wi-Fi signals are the primary cause of connectivity issues in smart thermostats, so by improving the signal can make a world of difference. To see if this is the case, check the signal strength using the Wi-Fi signal bars indicator on your smartphone or smart device. If your smartphone shows low Wi-Fi ...1. Verify that the thermostat is set to cool and is calling for cooling, usually indicated by the words "cool on," a snowflake icon, or a shimmering snowflake icon. If the room temperature is below the cool set point, the thermostat display should indicate a call for cooling. 2. Confirm that the circuit breakers are on.One is working fine while the other thermostat has power but won't run. It clicks when I set the temp as if it's starting to run or turn on but I get nothing. For reference I have a Honeywell intelligent T5 thermostat. Wondering if this is something I can troubleshoot myself as my AC guy is on calls for rest of today.Turn off your Honeywell Thermostat switch. Open the battery slot by pressing the door down and sliding it out. If this doesn't work, try inserting a coin or some similar object in the slot. Once you have opened the battery slot, slide the batteries out. Re-insert the batteries, but put them in a reversed position.How to Reset Honeywell Thermostat. Resetting your Honeywell thermostat is a simple and painless process. Begin by pressing the reset button on the side of the thermostat, then wait for the display to clear. Next, press and hold down both the “up” and “down” buttons until all segments of the display flash twice.Blink cameras are a popular choice for home security, providing users with peace of mind and the ability to monitor their property remotely. However, one common issue that users ma...7 Problems of Honeywell HZ311 Thermostat With Troubleshooting Guide. Problem 1: Incorrect Temperature Readings. Problem 2: Connectivity Issues. Problem 3: Unresponsive Controls. Problem 4: Heating or Cooling System Not Working. Problem 5: Display or Interface Issues. Problem 6: Short Cycling. Problem 7: Sensor Problems.

This portable air conditioner comes with everything needed, including a flexible exhaust hose and an easy-to-install window venting kit, which can be removed when the unit is not in use. See all Portable Air Conditioners. $589.99. Honeywell - 400 Sq. Ft Portable Air Conditioner - White/Blue. Model: MO08CESWB6.

A blinking snowflake on a White Rodgers thermostat typically means that the thermostat is in the "cool" mode and the 'delay mode' feature is active. This feature is designed to protect the compressor from starting too frequently, which can cause damage and reduce its lifespan. Under normal circumstance, delay mode doesn't take more ...If your Honeywell thermostat is blinking on and off, one potential issue could be related to low battery power. When your thermostat doesn't have enough power, it may blink a "Cool On" message or exhibit other erratic behavior. How to properly check the thermostat batteries. To check the batteries in your Honeywell thermostat, follow ... An improperly installed thermostat can result in various issues, including a blinking cool indicator without the cooling system functioning. Troubleshooting Steps. When your Honeywell thermostat is blinking cool on but not working, it can be frustrating. However, you can take several troubleshooting steps to try and resolve the issue. Step 2: Select the Desired Setting. Once you have entered the settings menu, you will need to select the desired setting for your override. You can choose from options such as ‘Cool’, ‘Heat’ or ‘Off’. Use the arrows to navigate the different options and press the ‘Done’ button when you choose your desired setting.Sep 19, 2023 · If the thermostat is blinking cool on but not working, this could indicate a power issue. Make sure to follow these steps to troubleshoot the problem and resolve it. Step 2: Check Thermostat Settings. When troubleshooting a Honeywell thermostat blinking cool on but not working issue, it is essential to check the thermostat settings. Air conditioning systems contain a finely tuned and balanced load of pressure, that when interrupted can cause problems to your system’s compressor. For this reason, there are safety measures put in place in the form of a blinking snowflake icon or “Cool On” message on the screen of the thermostat.Locate the system Slider Switch labeled Heat Off Cool. Slide the switch to the desired setting and either manually adjust the arrows to the desired set point and press hold or establish a schedule for heating and cooling.

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To resolve this issue, follow these simple steps: First, turn off the humidifier and unplug it from the power source. Allow the unit to cool down for a few minutes. Locate the water tank and carefully remove it from the base of the humidifier. Fill the tank with cool water up to the maximum limit indicated.If your Honeywell heater is overheating, it could be due to a dirty air filter or a faulty thermostat. Check and clean the air filter and ensure that the thermostat is set to the desired temperature. If the heater continues to overheat, it could be due to a faulty temperature control system. Best to contact an appliance repair person for help.Settings: Air Conditioning, Dehumidifying, Fan. The corresponding indicator light will illuminate to indicate the current mode setting. MODE CONTROL Air Conditioning Mode Adjust fan speed and air temperature to suit your desired comfort level. Temperature setting range is 16°C - 32°C (61°F - 89°F). • Dehumidifying ModeIf you have a heat pump, you will not use a wire in the W terminal. Move the W wire to the W2 or Aux terminal. (W controls your first stage of heating for Gas/Oil/Electric systems. O/B and Y control your first stage heating for heat pump systems. Backup heat sources must be connected to the W2, Aux, or E terminal for proper functionality.)Read online Honeywell Thermostat HZ221 User Manual pdf with better navigation. Printable and downloadable Honeywell Thermostat HZ221 user guide pdf. Model:HZ221 Page: 8. Download (PDF, Unknown) Model:HZ432 Page: 16. Download (PDF, Unknown) Note: For opening this Honeywell Thermostat HZ221 Manual, your computer need Adobe Reader. You can get the ...Lack of power - If your Honeywell air conditioner doesn't turn on, perhaps due to lack of power, then the compressor won't kick in, and as a result, the AC won't cool the space. Defective compressor - If you can't hear the compressor kick in when you power the AC on and it has taken more than 5 minutes, the compressor could be dead.So, when your Honeywell thermostat is in the blinking stage, it shows Cool-On for more than 5 minutes – But there is a feeling that the surrounding area is not cooling down, there is no cool air coming through the system either; you might need to fix the problem. Down below, we will divide the troubleshooting procedures into six quick steps.To resolve this issue, follow these simple steps: First, turn off the humidifier and unplug it from the power source. Allow the unit to cool down for a few minutes. Locate the water tank and carefully remove it from the base of the humidifier. Fill the tank with cool water up to the maximum limit indicated.A loose wire is one of the common reasons behind the Honeywell thermostat blinking the HEAT ON. When the thermostat blinks the HEAT ON, your device is in a 5-minute delay to give you heat. But more than 5 minutes is abnormal. The device increases the delay when the wires are loose and fail to signal your HVAC properly.Reset procedures vary widely depending on the model of the Honeywell thermostat, but they include pressing System to reconfigure the settings or temporarily inserting the batteries...The Honeywell Ac Thermostat Cool On Blinking Issue. Understanding the Honeywell AC Thermostat Cool on Blinking issue is crucial for maintaining optimal performance of your air conditioning unit. The blinking indicator on the thermostat serves as a warning signal and should not be ignored.honeywell hz221 zone 1 red linght blinking when i set thermostat to heating ... I get a red light for "Heat 1" indicating my heat is on, but my T-Stats are all set to cool. I feel cold air coming from the vents but the pipe leading away from my furnace is super hot. ….

Dec 19, 2018 ... This video shows you step-by-step instructions on how to program a Honeywell 2300B thermostat. Check out my video on how to install this ...Jan 21, 2020 ... Replace Batteries On A Honeywell Thermostat / Heat, AC ... "Cool On" Is Blinking on My Home's HVAC/AC Programmable Thermostat (Honeywell)➔ How ....Dec 20, 2023 · Leave the unit for a while and check whether the system is going to start cooling or not. Check other thermostat settings – something might have made your thermostat switch back to setup mode. Also, check the time on the device, as wrong settings can make the ‘cool on’ indicator start blinking. Replace the batteries or check the wiring ... Curious about your Honeywell thermostat's blinking 'Cool On' indicator? Decode the signal, troubleshoot, and keep your cooling system in check effortlessly. ... Clogged or dirty air filters can hinder your HVAC system’s performance, potentially leading to longer cooling cycles. Regularly replace or clean air filters to improve efficiency.If you're experiencing to Honeywell thermostat cool on scintillating problem, there are some solving steps that can help. Go this blog post for more info. 122-551-7894TH2110DV: For 1 Heat/1 Cool systems. TH2210DV: For 2 Heat/1 Cool heat pump systems only. (Pull thermostat from wallplate and turn over to find model number.) CAUTION: EQUIPMENT DAMAGE HAZARD. To prevent possible compressor damage, do not operate cooling system when outdoor temperature is below 50°F (10°C).To help clean the system, you can add a small amount of vinegar to the water tank and run the air cooler in evaporative cooling mode for 15 to 30 minutes; then, drain the tank of the vinegar water and refill with fresh, clean water, running on evaporative cooling mode for another 15 to 30 minutes. This will help to break down the calcium deposits.Jan 12, 2023 · 7 Steps to Troubleshoot a Honeywell Thermostat Flashing “Cool On” Message. 1. Check Thermostat Settings. 2. Check Your Thermostat’s Battery. 3. Set Your Thermostat to The Lowest Temperature. 4. Check If Both the Outdoor and Indoor Units Have a Power Supply. If your Honeywell Thermostat Vision Pro 8000 is having trouble, there are a few things you can do to troubleshoot the issue. First, check the batteries. If the batteries are low, they may need to be replaced. If the batteries are fine, then check the thermostat's settings. Make sure the thermostat is set to the correct mode (heating, cooling ... Honeywell ac blinking cool on, Leave the unit for a while and check whether the system is going to start cooling or not. Check other thermostat settings – something might have made your thermostat switch back to setup mode. Also, check the time on the device, as wrong settings can make the ‘cool on’ indicator start blinking. Replace the batteries or check the wiring ..., Change the batteries. Replace air filters. Check the furnace door/power switch. Inspect air conditioner coils. Replace the thermostat. Call in an HVAC specialist. Honeywell thermostat set to cool but heating. Confirm the thermostat is set up properly. Lower the temperature on the thermostat., , Easy Fixes for the "Cool On" Flashing Issue. Now that we have identified the potential causes, let's explore seven easy fixes to resolve the "Cool On" flashing issue with your Honeywell thermostat: 1. Check Thermostat Settings: Ensure that the thermostat is set to the correct mode (cooling mode)., Honeywell thermostats are among the best on the market because of their user-friendly display and reliability.The display is one of the highlights of Honeywell thermostats because useful information is readily available and it's easy to use.So, what does it mean when your Honeywell thermostat is blinking "Cool On"?The "Cool On" message will appear on your Honeywell thermostat if the ..., Why is the "Cool On," "Heat On," "Snowflake," or "Flame" blinking on the thermostat display? Last updated. 2/22/22. The thermostat has a built-in 5 minute delay to protect your equipment. If “wait” is in the screen or “cool on” is flashing – wait 5 minutes for the system to safely respond., All Honeywell thermostats, no matter the type of model, have a symbol showing you when the air conditioning is turned on. It can be a snowflake or it may say "cool on.". When the air conditioner is actually running it will be a steady symbol, but you may notice it flashing at times. This indicates that your HVAC system is in a delay mode., Check the circuit breaker to the part of the house which includes the T8000c thermostat. If it has been tripped, the thermostat isn't receiving power. This may be the culprit if the control display won't turn on, or no air is blowing to heat or cool the house. If you can't set the thermostat below 40 degrees or above 99 degrees Fahrenheit, don ..., All Honeywell thermostats, no matter the type of model, have a symbol showing you when the air conditioning is turned on. It can be a snowflake or it may say “cool on.”. When the air conditioner is actually running it will be a steady symbol, but you may notice it flashing at times. This indicates that your HVAC system is in a delay mode., Please try again. Check the name or model number of your product to ensure it's correctly written in the search bar above. If you're looking for a product that isn't a thermostat, try checking here., Steps To Troubleshoot Issues With ‘Cool On’: Honeywell Thermostat. The ‘Cool On’ indicator flashing on your Honeywell thermostat should normally resolve itself within 5 minutes. However, if that does not happen, you can use the steps below to troubleshoot the issue and resolve the problem. Set Thermostat To Lowest Temperature Setting, If the high limit switch is open due to overheating, it can cause the your Honeywell thermostat to flash “Heat On”. Troubleshooting will typically involve checking the high limit switch to ensure it is not tripped or stuck in the open position. If it is, allow the furnace to cool down and then reset the switch., Get expert help & support for Honeywell Air Comfort products. Access videos, manuals, and warranty with product registrations. ... Stay Cool. Get the latest news & exclusive offers when you sign up for our e-newsletter! I agree to receive newsletters, important info and promo content from JMATEK NA, LLC* ... Portable Air Conditioner Cooling ..., 2/22/22. If your thermostat is newly installed and the heat pump worked for cooling with the previous thermostat, check the following: 1. Verify that the thermostat is set to cool and is calling for cooling, usually indicated by the words "cool on," a snowflake icon, or a shimmering snowflake icon. If the room temperature is below the cool set ..., Gently remove the control panel and inspect the button contacts for any signs of damage or dirt. Clean the contacts if necessary and ensure a secure connection before reassembling the panel. 2. Erratic Temperature Control. Erratic temperature control is another common problem that Silverado owners may encounter with their AC control panel., To reset the system's schedule, press the System button. Next, hold the blank box that's in the center of the screen. When the numbers panel comes up, enter 0165 on the left and the number one on the right. Now press Done and your thermostat should have a reset schedule., The fan seems to be working, but no air comes from the vents and the fan outside for the outside is not spinning like the downstairs one is. HVAC Technician: gotoman for ac. It is probably getting late but check breaker on unit and also check float switch located on inside unit. It is set to open up and trip if drain backs up., Jul 2, 2020 ... HONEYWELL THERMOSTAT NOT TURNING ON AC SYSTEM merch = https://teespring.com/stores/steve-lav https://www.patreon.com/stevenlavimoniere ..., The filter can improve the system's performance or cause extensive damage when clogged with a significant amount of dirt. If the Cool On indicator flashes on your Honeywell thermostat, turn the air conditioner off and inspect the filter. A clogged air filter restricts the airflow into and out of the system, causing a malfunction., If you're experiencing the issue of the Honeywell thermostat cool on blinking, you're not alone. This common problem can be solved with a few troubleshooting steps. ... dirty AC coils can restrict airflow and lead to the cool on flashing issue. Inspect the AC coils and clean them if necessary. Remove any dirt or debris from the fins of the ..., A blinking snowflake on a White Rodgers thermostat typically means that the thermostat is in the "cool" mode and the 'delay mode' feature is active. This feature is designed to protect the compressor from starting too frequently, which can cause damage and reduce its lifespan. Under normal circumstance, delay mode doesn't take more ..., Select “Reset”. Select “Schedule Reset”. PERFORMING A HOMEKIT RESET. Press the Menu Icon. Scroll down to “Thermostat Information. Record the “Date Code”. Press the “back” arrow, then scroll down to “Installer Options”. Enter the Date Code when prompted to “Enter your password”. Select “Reset”., If you don't have it, you can contact the Honeywell customer helpline or research online according to your thermostat's model. Final Words. If you notice your Honeywell thermostat green light staying on flashing during installation, setting up, connecting to pairing to some device, or operating modes, it is entirely normal., Allow the AC to cool down before restarting to prevent overheating. Check Power Supply. Verify the power supply is stable and the unit is well-connected. Preventing Blinking Red Light. Honeywell portable AC blinking red light can be an unsettling issue that disrupts your cooling experience., Is you house HVAC thermostat blinking "cool on" or "heat on" and does not turn on the furnace or air conditioner? This is most often caused because power was..., Heat and cool settings must be at least 3 degrees apart. The thermostat will automatically adjust settings to maintain this 3-degree separation (called "deadband"). The 3-degree separation between heating and cooling set temperatures is fixed, and cannot be changed. Press system button until screen displays "Auto"., To help clean the system, you can add a small amount of vinegar to the water tank and run the air cooler in evaporative cooling mode for 15 to 30 minutes; then, drain the tank of the vinegar water and refill with fresh, clean water, running on evaporative cooling mode for another 15 to 30 minutes. This will help to break down the calcium deposits., 1. Reference your photo and documentation of your previous thermostat's wiring and confirm that there weren't any errors in your Lyric wiring. 2. Confirm that the provided AAA Lithium battery is still installed in your Lyric. Additional troubleshooting: Confirm that your wires are properly labeled. You can trace the wires back to the heating ..., Resetting your T5 Thermostat is an easy process that can be done in a few simple steps. First, locate the reset button on the thermostat. This will usually be located near the face of the thermostat or somewhere along its sides. Once you have identified this button, press and hold it for 10 seconds until you hear a clicking sound., The “Cool on” message on a Honeywell thermostat is also known as “delay mode”. It often flashes in the form of a blinking snowflake or as the word “wait’ as well. It’s a courtesy message to let you know that the AC will delay in coming on for approximately 5 minutes in order to protect your unit from short cycling which can cause ..., Blinking amber when there is a damper or ther-mostat short circuit (circuit breaker trip). EM HEAT Solid when in Em Heat mode. HZ221 2 Zones, 2H/1C LED Status Heat LED Heating Mode Flashing Heat LED High Limit Cool LED Cooling Mode Flashing Cool LED Low Limit Purge LED Purge Mode Flashing Purge LED Sensor Failure Fan LED Fan On Zone LEDs Green ..., Testing a Honeywell Thermostat. If the thermostat LED is lit, do a test by turning the thermostat to its maximum setting (in HEAT mode) or minimum setting (in COOL mode), turning the main control to AUTO or FAN and waiting for the blower to start. If it doesn't, remove the thermostat cover and check the wiring., Final Thoughts. The reason why Honeywell thermostat blinking cool on is maybe the thermostat devices taking delay time to prevent the AC from short cycling. However, the cool on flashing may indicate that the AC is pumping cool air into your home. The blinking is supposed to go away within 5 minutes.