Furnace Blower Keeps Running But No Heat

Two settings that you'll want to check are: 1) The fan setting. The wall thermostat has electrical contacts that control the power supply to the furnace. The furnace draws about 1. Make sure your thermostat is set to AUTO, not ON. Furnace Does Not Blow Air. Started having a problem last week where there tstat would reach temperature with the heater on, then tstat would quickly click twice and blower would keep running. actions · 2009-Dec-2 10:44 am ·. This usually solves the problem. If homeowners find this is beneficial, it is generally suggested to only run the furnace fan constantly during the cold heating season. Not enough heat: 1. I've tried that. Sometimes the fix is to run a power wire, other times. The furnace draws air from the surrounding area or from outside the room. In gas furnace, a burner heats ventilation air. Here is what happens, thermostat calls for heat, induction blower runs, igniter lites, burners turn on and nice clean blue flame emits from burners. Battery voltage on both terminals - Check speed switch and ground. If it is not then cobustion air is probably not an issue. I seem to have no control from the wall thermostat. And the real efficiency of them is actually around 75 to 85%, not much better than granny’s old furnace. A worn, wimpy belt isn't dangerous. If you feel no heat in the minutes after you activate your furnace, something could be wrong with the belt, heating coils or furnace settings. If You Smell Gas, Evacuate Immediately. By running your furnace blower on continuous air circulation, the heated air in the fireplace room will be distributed throughout your house. If you suspect a hole shut down your furnace immediately until you can test it. The limit switch is designed to detect the temperature inside of the furnace. You have a dirty filter and the high temperature limit tripped the furnace to run the fan constantly without heat to cool the furnace. Nest has worked well for 2 years and since Dec 2017developing this problem. Step 1: Locate your fan limit switch Your fan limit switch is located inside the furnace panel cover, usually near the upper right corner. If the heat exchanger (highlighted above) gets too hot, the furnace shuts down. If the blower continues to run when the temperature of the blowing air is cool, then the sensor that shuts off the blower is defective. Assuming your furnace is running normally, there is typically 60-90seconds sometimes 120 seconds depending on the control board dipswitch settings (if your control board has dipswitch settings) that the control board allows to gradually cool down. My heater is running, but no heat is coming out, just cold air. However, i am able to get the fan and heat going when i manually turn off and then turn on the furnace's electrical switch. I was sad to see my old dependable furnace go and was worried about this new one that needed electricity to run. Check the two terminals for the motor (Ignition in RUN, mode not in OFF, speed set to HIGH). In any case, many things can happen in that furnace sequence of operation that can prevent the gas furnace from providing heat. In an electric furnace, the thermostat activates heating coils instead of fuel to heat the air. Assuming your furnace is running normally, there is typically 60-90seconds sometimes 120 seconds depending on the control board dipswitch settings (if your control board has dipswitch settings) that the control board allows to gradually cool down. Free shipping and wholesale prices on our huge selection of air conditioning, heating and ventilation. The furnace may continue to run the fan blower to help cool itself off, or may not carry out any function until the system is reset or has cooled down sufficiently. However, this is not to imply that an oil burner won't develop a few ailments now and then, typically on. If the blower is running but no heat is coming out, replace the filter. Re: furnace - Duo-Therm will not light: ronald pearson: 9-1-06 : I have a model 90030-812 d duo-therm furance, 1985 year. Blower running but no (or little) air coming out Oct 20 2011, 12:26am This may not be the correct answer but I get the same problem on my work truck (2005 freightliner) and the problem is that if the a/c is used when temp outside is cool the a/c core or whatever the radiator type thing is under the dash gets frozen over and will not let the air. Be sure that you have changed your filter in the furnace recently. I opened the grill in front of the furnace, found the switch and turned it off. Like any good cheapskate, I hate turning on the furnace until the dead of winter. This afternoon I noticed it was very cold in the house (59 degrees) and I heard the furnace fan running. However, i am able to get the fan and heat going when i manually turn off and then turn on the furnace's electrical switch. Now the blower runs constantly, and though the draft inducer has 120 vac going to it, it will not turn on. The limit switch is designed to detect the temperature inside of the furnace. Regardless of what type of heating system, or the age of that system, you SHOULD get a winter tuneup. Turns out, the blower (or initial fan) runs but the heat does not come on and blow hot air. It doesn't matter if it is on auto or just fan same thing happens, with heater ok with A/C not ok. Today, for some reason, the heat just keeps running and the temp keeps going up and up and up. An internal sail switch senses low air flow and which cause the furnace not to ignite. Question: When we started to use our Carrier Comfort 80 a few days ago the blower came on but it never ignited the furnace so we have no heat. Then two minutes later it comes on again. I disconnecting wiring at thermostat but blower continued to run. How to troubleshoot a gas furnace. A dirty air filter blocks airflow over the furnace’s heat exchanger, causing it to overheat. Do not attempt opening a furnace yourself. If the draft blower fan on the front of the wood furnace is the one that is running all of the time feeding the fire. Found a pack rat working/building on top of furnace/duct work. A furnace blower motor that stops pushing warm air out is not the same as a blower that is forcing only cold air into your home. The two key improvements are: 1) reducing the amount of already-heated room air lost up the chimney and 2) directing more heat from the fire out into the room. This will result in no heat from the furnace or lack of a constant pilot light. Electric Furnace Runs Heat and Blower Constantly gas furnace fan keeps running - Duration: Gas Furnace Blower Not Shutting Off - Duration:. Gault said the first step to safety is making sure the heater or furnace is running the way it’s supposed to. When your furnace runs out of oil, it may or may not restart on its own after being refilled. a heating element). If you suspect a hole shut down your furnace immediately until you can test it. Knowing how to inspect the blower-fan belt improves furnace efficiency. I have to shut off the breaker for the furnace to shut off. It happened on three or four occasions and never happened again. After shutting off at the thermostat, the blower keeps running. Did your furnace fan stop blowing?. Dirty filters are the most common cause of furnace problems. After a power outage, my Carrier Gas Furnace blower motor will keep running, long after the burner has go out and cold air is coming out of the registers. The fan limit switch also has two other functions. Solution: Change the air filter and see if your furnace starts only blowing warm air. Posted By: Fishinghat on 09/07/10 09:57pm One of the signs of a low battery is the furnace doesn't cycle. I switched the heat on the other morning and the blower won't shut off at all. Blower on, thermostat says heating, but no heat I'm definitely a novice when it comes to HVAC, but have been noticing this problem happening intermittently the last week where my Nest thermostat says it is heating, but the fan is just blowing cold air through the house and the temperature keeps falling. It is considered OK to continuously run a furnace fan. The gas furnace will still cycle its burner to maintain the heat setting of that thermostat but the boiler 'stat is going to keep the fan running all the time. This furnace replaces a very old furnace (62 years). Yet so many homeowners do not know what to do to reap these benefits. I seem to have no control from the wall thermostat. 8 amps at 12 volts DC to run the blower. Fix Your Furnace If It’s Not Blowing Warm Air 42 This entry was posted in DIY and tagged Byant Currier DIY furnace blowing cold air furnace broken furnace ignitor furnace not blowing hot air gas furnace hot surface ignitor how to fix a furnace igniter Lennox Trane on November 4, 2014 by Steve Jenkins (updated 1795 days ago). Excessive heat in the motor can cause the motor to malfunction. A fireplace blower helps dramatically increase the efficiency of your fireplace by taking advantage of the heat that would otherwise be. The last time we. When the RV reaches the desired temperature, the burner will shut off, but the blower will keep running for a little while longer. Regularly inspect blower-fan belts for any sign of damage and replace the belt if it’s damaged. I cleaned the dust from the air intake upstairs. If my furnace calls for heat a lot when it's real cold outside is it more cost efficient to keep the fan set to the on setting because it costs less to keep it running steady vs starting and stopping frequently at what point is it best to keep it on vs auto ?. 5 to 3 minutes after your thermostat calls for heat and should turn off several minutes after the heating cycle ends. Assuming your furnace is running normally, there is typically 60-90seconds sometimes 120 seconds depending on the control board dipswitch settings (if your control board has dipswitch settings) that the control board allows to gradually cool down. If you have been experiencing electric furnace problems (specifically the furnace fuse blows when the heat turns on) throughout the holiday season, you might have assumed the problem is those cheap holiday string lights. It doesn't matter where the crack is, or its shape; when the blower is on, air gets pushed into the. After you have confirmed that the furnace is not the problem, you'll want to check the thermostat. Air from the home's ductwork is blown over the heat exchanger, warming the air. Would not shut off when set to off at thermostat. The most complete GAS FURNACE TROUBLESHOOTING & REPAIR guide w/easy instructions & videos for all GAS FURNACE TROUBLESHOOTING PROBLEMS & REPAIRS. Note: Start the test after system has been running for at least 10 minutes. The gas furnace in your home is the core of your central air system. RV Furnace Blower Comes on but Won't Ignite. Heat Pump check #2: Is the fan or blower running at all?. “Take the time to clean the furnace thoroughly. It won't equalize the heat, the living room is still much warmer than the bedrooms, but it warms the bedrooms a lot more than they would be without the blower running and it helps keep the living room from over-heating which is an issue in this well-insulated home. Hear a clicking sound from your furnace when it is running? This clicking sound in your furnace could mean your heat exchanger has a crack in it. On the other hand, the ECM technology in a variable-speed unit allows the blower to run at slower, more energy-efficient speeds, saving as much as 40 percent. Furnaces and boilers that are not sealed-combustion units draw heated air into the unit for combustion and then send that air up the chimney, wasting the energy that was used to heat the air. Occasionally a defective blower door safety switch can cause the furnace to stop working. If your heat exchanger doesn't get enough air, it can't transfer enough heat. In that case, you need to inquire about potential repairs. Here are still a few things that you can figure out yourself. A fan limit switch is a component of a furnace system that determines when the furnace blower assembly for hot air turns on and off. What to Do When a Gas Furnace Won’t Light. Furnace Failure Your furnace can fail to produce heat even if the blower continues to run, filling your home with recirculated air that is the same temperature as the. If you’re starting to notice a lack of performance, get the system checked out right away. It happened on three or four occasions and never happened again. I'm thinking electronic controller board could be bad. Would not shut off when set to off at thermostat. Transformer - Your furnace needs a transformer to convert to the correct voltage to run the ignition, controls, and timers. Also known as forced air furnaces, central heating systems distribute heat throughout your home through a series of ducts. Are you waiting long enough for the heat to actually come on?. Blower runs constantly with cold air until shut off manually with thermostat. Then that heat builds up and could end up causing your furnace to short cycle. Furnace maintenance should not be overlooked and is imperative to keeping the system running properly. On a call for heat, the burner lights, the fan control closes, but the blower does not run. It is considered OK to continuously run a furnace fan. Burning propane or natural gas generates heat in the furnace's burner. My Electric furnace will not shut off. With the cold weather season quickly approaching, there’s no better time than now to double check that your furnace is running smoothly. Regularly inspect blower-fan belts for any sign of damage and replace the belt if it’s damaged. Today, for some reason, the heat just keeps running and the temp keeps going up and up and up. Keep in mind that the power for blower motor for the furnace is most likely provided from a separate circuit or receptacle. thanks in advance i have this york roof top DH090N15 the belt was broken i replaced but now soons i open the power it try to run heat even the thermostat its calling for ac (exhaust blower and fan motor runs but not heat), i disconnect all the wires on the board but it still run the fan and exchausr blower by itself. There could also be a low battery, a bad wiring connection, or a restricted ventilation system. It just keeps blowing heat. I put a new one on for him, and now, compressor and outdoor fan run properly in heat or cool mode. After ruling out all of the 'simple' problems above, the most likely cause of a furnace not blowing air is a problem with the blower fan itself which, if you remember, is the fan that circulates your house's air over the heated coils. We also had the blower motor cleaned as it was running out of balance, but after cleaning, seemed to be running smooth and true. I have to go upstairs to the hallway and unplug the furnace from the outlet to shut off the fan. Check Your Furnace Blower Motor. Although the heat exchanger in the furnace is not running when your AC system is running, the blower wheel in your gas furnace pushes air through your home. Because your system is not shutting down on your draft motor or pressure switch it is not likely that you have a bad fan or blockage so that leads me to a possible bad heat exchanger. 5 Warning Signs You May Need to Replace a Furnace. This means the fan will run but no heat will be. A dirty furnace filter can cause a blower to keep running long after the furnace shuts off due to an excess buildup of heat. From what I guess of your explanation, your furnace is not producing any heat and the room air blower runs blowing cold air. Furnace blower motor hums and won't always start Eventually the hi temp sensor will kick in and turn the gas off.  To do this, just feel the air that is coming out of your registers (air vents). Wiring: Y1 black (AC), W1 White, G green, Rh Red. Our furnace comes on but it blows cold air for a few seconds then shuts off. It definitely makes a difference and I recommend it. The temporary replacement furnace had a forced-air blower, but it made just barely enough heat to get the garage up to 45 degrees and it took several hours to reach that not-so-comfortable point. A faulty element, for example, is a critical part for proper comfort control. We offer support before, during and after the sale, 365-day returns and price match plus guarantee. The thing started acting up where after the furnace would cycle the blower would come on briefly for a couple of seconds then turn off about 3 times within about 10 seconds. Check your thermostat. Mobile Home Furnace Blower Will Not Come On. If the air blower and ignitor are working, but there is no heat, the two lights will show slow alternate blinking. No heat, blower runs constantly, carrier gas furnace [ 7 Answers ] This am we I got up the blower on my carrier series 100 gas furnace (approx 10 years old)was running and blowing out cold air. Your wood furnace company. When switch the breaker back on, the heater will work properly for a short time and then do it again. It happened on three or four occasions and never happened again. Since I really do not understand these things, I will appologize now if I ask a stupid question. Loud Furnace Causes & Solutions Blower Motor. As much as we may hate to admit it, fall is here. All too often, restoring the flow of warm air is simply a matter of opening heat registers. If it is humming but no air is coming through the vents, it might be lighting the burner, but without the blower to circulate the heat. Just contact us and we can get your furnace fan running normally in no time. The furnace draws about 1. I'm fairly handy and feel comfortable troubleshooting and fixing stuff, but I'm a complete n00b when it comes to furnaces. If furnace has electric-eye safety, clean safety; if no result, call a professional. The sail-switch is a safety device that turns off the propane if the furnace loses 12V power (no 12V power = no fan = no way for the furnace to cool itself off, so the gas still burning in a furnace that has lost power could be a dangerous situation, hence the sail-switch). I have to admit that this furnace is doing a good job of keeping us warm and uses a lot less gas. We've encountered a number of situations where manually pressing and releasing the safety switch was enough to get the furnace back up and running again. A fan limit switch is a component of a furnace system that determines when the furnace blower assembly for hot air turns on and off. This report is intended to take the mystery out of energy efficient HVAC systems (SEER, HSPF and AFUE ratings) so that you can make an intelligent and competent decision. Time delay relay. Today, for some reason, the heat just keeps running and the temp keeps going up and up and up. You see, ON forces the blower to run 24/7 whereas the AUTO setting only runs the blower when your furnace is on a heating cycle. A furnace contains an internal sail switch, that senses the air flow. This means the fan will run but no heat will be. However, as the HRV system runs continuously, why do I need to run the furnace blower continuously? What would be the potential problem if I put my furnace fan in an auto mode?. Because your system is not shutting down on your draft motor or pressure switch it is not likely that you have a bad fan or blockage so that leads me to a possible bad heat exchanger. Furnace Running Constantly? Whenever a cold snap hits – lower than 25 degrees here in Atlanta Metro – your furnace or heat pump may seem to run constantly, leading you to believe that perhaps your unit is too small and unable to keep up. 5 to 3 minutes after your thermostat calls for heat and should turn off several minutes after the heating cycle ends. This furnace replaces a very old furnace (62 years). Your thermostat fan setting should be set to AUTO, not ON. Furnace Does Not Blow Air. This is probably a sail-switch issue. This could be because of insufficient air flow in the furnace. Check your furnace by turning on the heat and the blower to be sure they're operating as they should. The circuit board, or control board, is basically the brain of a furnace. 4 Steps To Troubleshoot Furnace Blower Motor Fan And Repair Replacement Guide When it comes to the cooler months of the year, heating becomes essential and if, after not being used for some time, you go to turn on your furnace heater, only to find that no heat or air comes through the vents, then, as explained in the HVAC Blower Motor Guide. air conditioners run for less. Every time the thermostat makes a call for heat, it will indicate this an arrow pointing towards System On in the display. Most furnaces should be relatively quiet when they're running. Definition of a Fan Limit Switch. Regularly inspect blower-fan belts for any sign of damage and replace the belt if it’s damaged. Excessive heat in the motor can cause the motor to malfunction. No matter how you travel to work, whether it’s by bus, car or train, your commute probably ends with a cold walk in the icy wind. Helpful Questions to Ask on No Heat Calls May 8, 2015 If the fan is not running, there may but is not producing any heat, the furnace may not actually be. Heat exchanger—This creates the heat for your home. The thing started acting up where after the furnace would cycle the blower would come on briefly for a couple of seconds then turn off about 3 times within about 10 seconds. Furnaces commonly overheat as a result of the following conditions: Running for long periods: The colder it is outside, the harder and longer your furnace will run to keep the. If the furnace were to run full time over a very cold night, it would use 18 amp-hrs from the house battery. Helpful Questions to Ask on No Heat Calls May 8, 2015 If the fan is not running, there may but is not producing any heat, the furnace may not actually be. Thermostat settings have no effect. Gas and Oil Home Heating Furnaces - Carrier Furnace: Fan runs continuously, No heat - Hi, My furnace is a Carrier 58PAV070-12. It is important to note that constant overheating can damage your heat exchanger. The Thermostat reaches the Set Temperature and opens. First of all, I might say that if your furnace is electric, then I think you will need to take a closer look at the breaker. Our furnace comes on but it blows cold air for a few seconds then shuts off. In any case, many things can happen in that furnace sequence of operation that can prevent the gas furnace from providing heat. The refrigerant pressures are typically measured at the service valves at the ac condenser. If the high limit switch goes bad, the furnace won't shut down and the heat exchanger will crack. Gault said the first step to safety is making sure the heater or furnace is running the way it’s supposed to. After shutting off at the thermostat, the blower keeps running. To the second post, does it happen all the. After firing off again, I would then have to do the same to shut the blower off. Pilot won't stay lit. But if your fan runs constantly, regardless of whether your furnace is heating, that's not normal. Homeowners should experiment to see if it works best for their home to have the furnace fan running continuously or not. Your thermostat fan setting should be set to AUTO, not ON. Furnace Does Not Blow Air. I opened the grill in front of the furnace, found the switch and turned it off. This will result in no heat from the furnace or lack of a constant pilot light. A faulty element, for example, is a critical part for proper comfort control. If after trying a second time to run the furnace you get no heat, I suggest calling a qualified tech. Be sure that you have changed your filter in the furnace recently. I put a screw driver in the fan (outside) and pulled it through like a prop start on an airplane, the motor turned on and the furnace ran again for 24 hours. With a versatile, dual-fuel design that lets you choose between liquid propane and natural gas, the heater warms up to 1000 sq. Finding a furnace, boiler or heat pump problem before the weather gets cold prevents a no-heat disaster — plus paying for a tuneup (and any maintenance) will ALWAYS be cheaper than paying for an emergency repair. Fall has officially begun, so before the cold hits for good, you'll want to winterize your home to make sure the furnace is in good repair and that any cracks and crevices in your home are sealed. (The white square at upper left portion. Motor overload. Maintenance helps to keep your unit running efficiently and, ultimately, saves you money. The two key improvements are: 1) reducing the amount of already-heated room air lost up the chimney and 2) directing more heat from the fire out into the room. Now the blower runs constantly, and though the draft inducer has 120 vac going to it, it will not turn on. If you’re starting to notice a lack of performance, get the system checked out right away. Thanks in advance I need help with furnace, no heat ? - iRV2 Forums. Your furnace may be blowing cold air because the filter is too dirty. Raise thermostat setting 5°. Remember, your furnace needs electricity to run, just like your refrigerator and your microwave. A dirty filter will also cause soot to build up in the heat exchanger, causing your furnace to run inefficiently and reduce it's life span. Also known as forced air furnaces, central heating systems distribute heat throughout your home through a series of ducts. Our furnace starts blowing cold air as soon as the blower comes on then in a couple of minutes the furnace lights. When switch the breaker back on, the heater will work properly for a short time and then do it again. A furnace has two leads to the t'stat, they are either open, no heat called for, or closed, need heat. Battery voltage on both terminals - Check speed switch and ground. My heater is running, but no heat is coming out, just cold air. How Your Fan Normally Works. Do the following: 1 Be sure the thermostat is set to the proper setting ("Heat" if you're calling for heat) and the temperature you want the room to be. SUBURBAN DYNA-TRAIL FURNACE OPERATION AND TROUBLESHOOTING By John Nicholls DISCLAIMER Information presented by GMCES is intended only to communicate thoughts, ideas, opinions and procedures to and from GMC owners; there is no attempt to replace or supersede recommendations from General Motors Corporation or any other component manufacturer. Dirty filters are the most common cause of furnace problems. Check the filter first. After you have confirmed that the furnace is not the problem, you'll want to check the thermostat. I’m currently having trouble with getting heat. Do you mean the furnace blower (fan) won't turn off? Or do you mean the furnace burners won't turn off? We'll tackle these separately. Wiring: Y1 black (AC), W1 White, G green, Rh Red. I disconnecting wiring at thermostat but blower continued to run. No heat in the water, the fan cant run. Furnace motor capacitor looks good. The furnace draws about 1. A tank with very little gas or an issue in the gas line can lead to low gas pressure. Transformer - Your furnace needs a transformer to convert to the correct voltage to run the ignition, controls, and timers. When your furnace runs out of oil, it may or may not restart on its own after being refilled. NOTE that working inside the air handler cabinet of a heat pump and working with electrical parts can be dangerous, so if you feel out of your element, it’s always after to call a heating repair technician. Blower motor decided not to shut off during furnace operation-keeps running even after temp set point reached. I have a Coleman furnace model 3500-816, Serial Number 088878254 (54,000 btu's). Pilot stays on but the furnace doesn't come on, step 1. Heat Pump check #2: Is the fan or blower running at all?. This is a safety item to make sure there is not a build up of propane in the furnace that could cause an explosion. Control is via a conventional low voltage, wall mounted thermostat. If the burners DO light, they will then go out if the blower does not come on. Your furnace is running because it’s out of shape!! In all seriousness, this statement is actually true. First of all, I might say that if your furnace is electric, then I think you will need to take a closer look at the breaker. The furnace's blower then forces the heated air into the supply ductwork, distributing it throughout the home. First make sure there is power to the indoor unit and that a switch or breaker isn't off. Make sure your thermostat is set to AUTO, not ON. This is a $15 part. Air is always pushed into the heat exchanger whenever the blower is running. Both come out the rear of the furnace, which must be fairly close to the side of the van. So what causes the furnace to overheat? Most commonly, a dirty furnace air filter. (If the thermostat is in the "cool" position, the furnace blower should be running. This report is intended to take the mystery out of energy efficient HVAC systems (SEER, HSPF and AFUE ratings) so that you can make an intelligent and competent decision. Are you waiting long enough for the heat to actually come on?. Even with the thermostat turned to off the blower runs constantly. I’m currently having trouble with getting heat. The above photo will give you an idea of where the furnace blowers are. I was sad to see my old dependable furnace go and was worried about this new one that needed electricity to run. Posted on: September 20, 2019 | by: Will Housh It's getting cold, so that means it's time to make sure your furnace is up to the task of keeping you warm this winter.  If it is hot, then this is not your problem so move on. Shut down the furnace, check the belt, and put just a few drops of electric-motor oil in any oiling ports on your firing assembly fan (some sealed units run oil free, so you may not have ports). I would shut the breaker off and then it would be okay. A faulty capacitor will not be able to hold the charge necessary to run the blower motor properly. Every time the thermostat makes a call for heat, it will indicate this an arrow pointing towards System On in the display. When it gets very cold they can frost up. So, when the switch is working correctly, your furnace fan should turn on several minutes after thermostat calls for heat and turn off several minutes after the heat cycle ends. It might have a fuse that is blown on the blower part of the furnace. There is no need to use unsafe portable electric heaters to supplement your heating or freeze protection. Trying to get my furnace running. If it happens to be low power, I merely replace the battery with a one that has the right voltage. However, this fix is not common and often requires that the switch be replaced. ON makes your furnace's blower run non-stop but AUTO will tell your furnace's blower to run only when heat is being produced, so it should shut off once your home reaches the desired temperature. Something like hooking the white wire to the G or R terminal. Then, check to be sure that the thermostat is set to a temperature high enough to trigger the furnace to emit heat. The limit switch is designed to detect the temperature inside of the furnace. (We know it’s tempting, but your furnace room is not supposed to be a storage closet. Currently with the thermostat I can have the fan run all the time but it is on the same speed as when the heat is on and I would like to know if it is possible to have the motor run 24/7 on low and when it needs to kick in for heating then run on high or med high as it is now?. Then two minutes later it comes on again. familyhandyman. Blower on, thermostat says heating, but no heat I'm definitely a novice when it comes to HVAC, but have been noticing this problem happening intermittently the last week where my Nest thermostat says it is heating, but the fan is just blowing cold air through the house and the temperature keeps falling. I have to go upstairs to the hallway and unplug the furnace from the outlet to shut off the fan. I took the outside cover off to find the blower and motor but i didn't want to go any farther until i asked. A slow motor speed could be caused by a low battery or other low voltage cause such as a bad connection in the wiring. You get in, start the engine, turn up the heat control, and adjust the fan speed to medium and to your surpriseno air is coming from the defroster vents. When you say the furnace is still running, I take that to mean the fan and not the actual flame portion of the furnace. The furnace sounds like it's running intermittently: Check the air filter first. If this did not happen the heat from the Heat Exchanger would cause the furnace to go off on High Limit. Fast forward. Gas and Oil Home Heating Furnaces - Carrier Furnace: Fan runs continuously, No heat - Hi, My furnace is a Carrier 58PAV070-12. System not cooling enough: Check the filter for buildup. When the unit is in the cooling mode, the draft is not so undesirable, but. The fan limit switch is responsible for turning the blower on and off at the appropriate times. Its running (the fan), but there is no hot air coming out of the vents. By Gary Motley. Furnaces and boilers that are not sealed-combustion units draw heated air into the unit for combustion and then send that air up the chimney, wasting the energy that was used to heat the air. The simplest thing to do is to open up your manual and see if your furnace has a 'G' terminal. Since you're plugged in, I would suspect your inverter/converter isn't putting out 12. This will cause the motor to run slowly, causing excess heat. Pilot won't stay lit. Replacing it is an easy fix. Hello Ford Mechanics at large, I own a 97 Ford Ranger and about two weeks ago the cab blower fan (for the Heat and A/C) started to intermittently fail. Furnace keeps running. After firing off again, I would then have to do the same to shut the blower off. You can spray it with Beauty Tone clear lacquer and make it nice and quiet. Not - Answered by a verified HVAC Technician. Helpful Questions to Ask on No Heat Calls May 8, 2015 If the fan is not running, there may but is not producing any heat, the furnace may not actually be. But now the furnace (fan or heat) is not turning on even when i set the temperature on the thermostat higher than the temperature at home. If the burners DO light, they will then go out if the blower does not come on. You don’t have to worry about a 1500ºF flame burning inside a metal cabinet in your RV.