Finally, reattach the sensor and restore power to the furnace. There’s also nothing like the disappointment of discovering your furnace blowing cold air inside when it’s turning cold outside. If you continue to have problems associated with duct leakage or your furnace blowing cold air, an HVAC professional can provide a more sophisticated analysis and duct sealing options for ducts that are not easily accessible. This may happen if you forget to make a payment. It could even be running in the air conditioning mode due to a malfunction. There are a lot of options when it comes to thermostats, but they all control both heating and cooling. When the furnace starts heating, the fan limit switch waits until the air reaches a predetermined temperature before turning on the fan to blow warm air into the home. You might be able to tell if your ducts have a leak, but fixing them is another issue. This article applies to the Ford F-150 (2004-2014) and F-250 (2005-2014). Tim H., HVAC Professional. Then, check to be sure that the thermostat is set to a temperature high enough to trigger the furnace to emit heat. 8 Common Problems With Conventional Gas Furnaces, Troubleshooting an Electronic Ignition Furnace That Won't Light, Troubleshooting an Intermittent Pilot Ignition System, How to Light the Standing Pilot Light on a Gas Furnace, How to Troubleshoot Electric Ignition Furnace Problems, How to Replace a Furnace Thermocouple or Electronic Flame Sensor, How to Check a Pilot Light on a Gas Furnace, Troubleshooting Common Problems With a Gas-Fired Hot Water Boiler. The lukewarm air coming out of your furnace can also be the result of leaky air ducts. Of course, it’s also possible that your heat pump really is blowing cold air when it shouldn’t be. Coolant level is good. Unaddressed, dirty furnace filters can cause extensive, and expensive, damage to your home’s heating system. Or the gas line isn’t supplying enough gas to your furnace. The nest seems to blow warm air normally but once it switches to alternative heat source, then it starts blowing cold air. Closed heat registers can cause other issues, as well. The sound you hear is the reversing valve switching your unit over to cooling mode. There are many reasons your car's heater isn't working. Heat coming out on driver side only, cold air blowing out on passenger side. This can cause the air to feel only lukewarm. Below is a list of possible causes. The fan setting on your thermostat has two options, “on” and “auto”. Answered in 1 minute by: 11/2/2012. The hot coolant flows in one side of the heater core and out the other side headed back toward the engine. Another common problem is when air gets into the cooling system. Change your furnace filters regularly to ensure that your furnace continues to work properly. If so, your system may be circulating cooler air between heating cycles. When overheating, your furnace can trip a high limit switch, causing the furnace burners to shut off so that the heat … Simply turn your system on, and hold your hand over joints, connections, or anywhere you can visibly see a seal in the ductwork. Either of these would be a clue that a malfunctioning flame sensor could be causing your furnace to shut down. Alternatively, they may have experienced a computer or clerical error that made them think you haven’t paid yet. A furnace that frequently shuts off automatically may have other issues, such as a clogged air filter or blocked ducts that are causing the furnace to overheat. If the heater is blowing cold air and the car is overheating, it is likely that the problem is related to the engine cooling system as well. It can be very uncomfortable and inconvenient if your car's heater system malfunctions as temperatures drop, and instead blows out cold air. If none of these simple issues seems to be to blame when your furnace stops producing warm air, then there may be more complicated problems. First, confirm that the light is out. This function allows the furnace to warm up the air before the blower pushes it out through the ductwork and into your living areas. To clean the sensor, turn off power to the furnace at the breaker box. The coolant supply is blocked. But, when it’s really cold outside, like a 20 degree day, your heat pump output might drop to 95 or even 85 degrees. Automotive Mechanic. It’s a natural phenomenon for heaters or air conditioners to blow out room temperature air right after they are turned on. Of course, for every reason a perfectly operating furnace is blowing cold air, there could also be a more serious issue lurking. Looking for the thermostat I found a weird piece on top of engine called a coolant outlet housing, has a bleeder valve on top. Typically, the flame sensor comes in the form of a rod that can be found near the back of the furnace, right in the path of the burner. fan speed, and vent option. Ensure that there is actually a problem when your heat pump is blowing cold air. Most cooling systems have a bend door that controls the flow of the air through the heater core. But if you have an older model furnace, your home is too cold and the furnace hasn’t turned on, your pilot light may be out. Try opening all of your heat vents and see if that solves the problem. There are two possible routes here, one of which many homeowners who are new to heat pump systems encounter. DON’T ignore this problem. Depending upon the age, condition and quality of the construction, your home’s ductwork may have some significant leakage. If the fan limit switch malfunctions, the blower might continue to operate even when the furnace is not heating the air resulting in your furnace blowing cold air from your registers. Also if your water heater has issues, you can check out this Water Heater Troubleshooting Guide to efficiently solve the issue. Look to these possible causes one at a time. The pilot light might simply just need to be re-lit, or the gas valve could have been shut off after last season’s use. Air in the cooling system impedes the circulation of coolant in the system, and as a result, the heater blows hot air only when driving, and cold air at idle. Car is overheating Inspection: $79.99 - $89.99: Get a Quote : Marvin Sunderland. Compromised flame sensor. The flame sensor’s job, as its name suggests, is to detect a flame from the burner. This can cause your furnace to lock down for safety. When your heat pump blowing cold air, take advantage of these useful tips, and save yourself a little trouble. My heat does not work it blows cold air and the heater and air only work on high. If you can see the burner in your furnace, you may be able to visually inspect the flame sensor for cracks in its porcelain base, or soot build up on its tip. 3) Pilot light is out If your gas furnace is only blowing cold air, then the pilot light may be out. As a result, any air that blows out of the vents while your heater is off will usually feel cold. Check the Pilot Light on Gas Furnaces. The heat from the hot coolant is what your heater normally blows throughout the inside of the car. Is it set for air conditioning instead of heating the air? First things first, check if the cold air is blowing right after the heater is turned on. Your gas supply could be turned off. If you still suspect the problem is a dirty air filter, consult your owner’s manual for instructions on removing and cleaning or replacing your air filter. Just not sure where all the water goes so fast with no leak. In other words, it's not putting out any heat at all. If it does, and you still want to close a few vents, try closing fewer vents this time. Your furnace blowing cold air could be caused by hot air escaping through holes in the duct work that carries the heat throughout your building. Learn about our energy efficient innovations that can help you save on your heating & cooling energy expenses, while ensuring your home is comfortable. If you have an older furnace with a standing pilot light, it’s possible that the pilot light is extinguished. If your car is blowing cold air that means that, the hot coolant is not reaching the heater core. The heater blows cold air. If you’ve checked all of the easy-to-remedy reasons that can result in your furnace blowing cold air and you still haven’t solved the problem, it may be time to contact your local Carrier® indoor comfort expert to see if your furnace needs to be serviced, adjusted or replaced. Two Reasons Your Heat Pump Is Blowing Cold Air. Why a Heat Pump Will Blow Cold Air. Perhaps your temperature gauge is running below normal. The heat pump is blowing cold air when the thermostat was set to heat. Dust and debris inside the thermostat can cause it to malfunction. Try kicking it up a notch to see if there’s a noticeable difference. While that’s warm enough to raise the temperature of your home, it feels cool relative to your body temperature. Check the furnace’s air filter. To troubleshoot a misbehaving gas furnace, start with the easiest explanations and solutions, then work your way to the most complicated. Have an expert inspect your ducts along with the furnace. With all of the options available, there are a number of scenarios involving your thermostat that can result in your furnace blowing cold air. Learn about our innovative products and how they can help improve your comfort. Leaky ductwork not only leads to reduced comfort, it can result in higher utility bills because of the amount of heat lost due to the leakage. Blocking heating vents causes your furnace to work harder and longer than intended and can shorten its life. We wanted to address this, as many times homeowners think this is an issue with their heating and cooling system, but if they have a heat pump, it's actually A dirty flame sensor may cause your furnace to function improperly. Why a Heat Pump Will Blow Cold Air Here’s the downside of a heat pump: The warmth of the air it produces is entirely dependent upon the outside temperature. Your furnace may be blowing cold air because the filter is too dirty. Maybe the fan is malfunctioning. Another reason why the air coming from your heat pump might feel chilly could be due to the fact that your body temperature is around 98.6°F and heat pumps blow air that is a temperature below that. Your gas supply could be turned off. Major duct problems. If the heater has a tap for supplying coolant to the radiator, then this is closed or jammed because of rust. Share this conversation . 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