Most vehicles today require a 190 to 195 degree F. thermostat. On vacuum-actuated systems, the vacuum motor or control switch may be defective and require replacement. If your car is running low on coolant, if there’s air in the system or if the core itself isn’t working properly, then this could be the cause of your car heater not working. • A blower fan that isn’t working properly. If the valve fails to close, replace it. All power to every one of the electrical working parts of the car is supplied via fuses. Connect one wire to ground and the other to a source of battery voltage. either expressed or implied, including without limitation any warranty of merchantability or fitness for particular purpose, with respect You should feel no coolant moving inside the hose until the engine starts to get warm. Step 4 - this problem happens more than I thought at first, but after reviewing many posts with the same problem the fix was relatively simple. If your heater isn't working, the coolant level may be too low, the heater core could be clogged, a heater by-pass valve may not be opening, the doors in your hvac system may not be moving or if the thermostat is stuck open, it will cause a temporary lack of heat. © 2020 AutoWeb, Inc., all rights reserved. Along the same lines as the coolant system issues, a malfunctioning thermostat could also cause your car not to have heat. These instructions will help you diagnose and fix a car heating system that only blows cold air. As the engine gets hotter, so does the coolant. commercial purpose whatsoever without the express written consent of Chrome Data. A problem with the switch which turns the fan on or off, might also be the source of the problem. © That's because removing the coolant cap on a hot pressurized system can result in severe burns. A different reason for the heat to not work would be a lack of coolant going through the engine. A heater that's working properly should blow air that's about 75 to 100 degrees F. hotter than the outside air. The thermostat should open and close as the engine temp moves up. The most common culprit for your heaters not working is a faulty thermostat. Electrical problems such as a blown fuse, defective power relay, heater switch or resistor, or a loose wire should also be checked. The car's heating system consists essentially of a motor-driven fan to blow warm air from the engine bay to the car's interior. Find the procedure in a shop manual (at auto parts stores for about $20). Counterintuitively, the same system that keeps your engine cool is responsible for the heater working. Reasons Your Car Won't Heat | Heater Stopped Working. Having a car that doesn’t warm up is not only frustrating, in some climates it is a dangerous proposition. Shorts, broken dials, and bad touchscreens can all … Check for blown fuses and replace them to restore normal functionality. Check to see if the coolant is circulating through the heater core by feeling both heater hoses. A lack of heat can be a symptom of a much larger problem. An air pocket in the heater core or a heater hose may be interfering with the flow of coolant through the heater core. Instead, you might have a failed thermostat, which opens and closes circuits in the cooling system as the engine heats up. Always use a replacement fuse with the same amp rating as the original. If the fuse lasts a while and then blows, the fan motor is probably running hot due to worn brushes and/or bushings and should be replaced. Perhaps your temperature gauge is running below normal. If the fuse is blown, therefore, find out why it blew before replacing it. Turn off the vehicle and let the engine cool completely. Check to see if the thermostat is stuck open. Distilled water is best since it contains no minerals. If the thermostat is “stuck” it can close off all coolant to the engine…thus overheating and no heater heat will result. After several minutes, you should feel a sudden surge of hot coolant when the thermostat opens. Blower still does not work. So, a problem with the vehicle's cooling system might also cause the heater to underperform or stop working. Simply put, your car’s buttons, knobs, or haptic feedback touchscreens may not be triggering the heating system. Coolant (AKA antifreeze) flows through the engine, absorbing heat from the rapidly-moving parts inside. It is not currently accepting answers. 2. A small amount of hot coolant is diverted into a hose fitted into the firewall and then into a small heat exchanger or heater core. Although a leaky or weak radiator cap can be the culprit, a low coolant level may also be the result of not getting the cooling system completely filled. Accumulated debris in the cooling system may plug the core and block the flow of coolant. So my car is at a DMC vendor getting worked on. Rotated all the unmarked relays around in the junction box. Disconnect the wire where it joins the heater element and probe the wire with the test lamp. The bottle in that case does the same thing as the funnel as explained in the repair video. If the pressure cap is located on the reserve bottle and not the radiator the Lisle funnel will not help. If one or more of these issues is present, your vehicle may blow out cool air rather than heat: Not enough coolant in the engine; Problems with the heater core; Clogged or broken heating controls; Dysfunctional thermostats This allows coolant to circulate through the heater core even when the heater isn't being used. This information is supplied for personal use only and may not be used for any There are a lot of different ways a car heater can fail, but the problem you’re describing is usually caused by one of two basic problems. Check the control valve by applying a vacuum with a hand pump. Opening the valves allows air to escape as the system is filled. If your car has not been overheating or running hot, your water pump is not the culprit. A weak water pump, one with corroded impeller blades or one that doesn't turn fast enough because of a slipping drive belt may be another possibility. Venting trapped air can help. This question needs to be more focused. There is no battery to operate the blower. Chrome Data makes no guarantee or warranty, A blown fuse might just be the reason your car heater fan is not working. Closed. The symptoms could be an over cooled radiator and a roaring sound at higher speeds. Top Five Winter Car Care Maintenance Tips. Both the inlet and outlet return hoses should feel hot when the engine is at normal operating temperature and the heater is on. With the engine running at full temp jack the front of the car up and let it run for 2 minutes then go to the rear of the car and do the same thing, this will burp or purge the air bubbles locked in the heater core and allow the heater to work again. Ken Mattson, owner of Len’s Automotive in Bellevue, Wash., says a car heater can stop working for a number of reasons, including: • A low antifreeze/water level in the radiator due to a leak in the cooling system. Checked for battery at the blower, when the car is running. Viewed 12k times 1. Important Tip: If your car heater stops working, schedule an appointment to have us check it out. Start a cold engine and feel the upper radiator hose. 2012 Chrome Data Solutions, LP. Checked continuity of 40 amp blower fuse; it's okay. If the fan isn’t working, you probably need to have the blower motor fixed or changed. Check the coolant level. Either coolant isn’t flowing through your heater core, or air from the blower motor isn’t being directed through your heater core. Refilling some cooling systems can be tricky. Some front-wheel drive and rear-engine systems require special filling procedures to eliminate the air pockets in the heater hoses and heater core. The only cure here is to replace the heater core. All specifications, prices and equipment are subject to change without notice. A new door actuator costs less than $100. A car heater works by blowing air from the heated engine over a heater core and funneling it into the vehicle compartment. Check the electric cooling fan and clutch fan to see if they are stuck. A Lisle coolant funnel can be used to burp air out of the system if the pressure cap goes directly on the radiator in your system. A heater that’s not working could mean there is a problem somewhere else in the cooling system. You can usually diagnose and fix the problem yourself in about an hour. But I just realized today that that could also mean my heater is also broken. Make sure your heater is working properly before extremely cold temperatures set in. There could even be a puddle of liquid under the front of the vehicle. All components need to be functioning properly for the air to heat the car interior fully. If the defrosters aren't working either, you can likely fix the problem by reattaching or repairing a loose cable or vacuum hose. Active 3 years, 2 months ago. If a thermostat is stuck in the closed position, it will never allow coolant to circulate fully, so no heat for you. If no feed is evident trace the route of the wire back along the car and probe it at various intervals until you find the break or loose connection in the wire. Rotated all the PDC relays around, they have the same ID, other than ABS pump. When a car heater doesn't work, the most common cause is low coolant. Because we rely on the coolant system to provide us with heat through our heaters, there are now a few components that can fail and mean that you'll never get heat out of your car heaters. Now, if the upper radiator hose is hot but the lower hose and the heater hoses are cold then try a new thermostat and see if the issue is repaired or not. • A bad thermostat that isn’t allowing the engine to properly warm up. A car heater that isn't working could be caused by several simple issues. And you wait — and wait — but the heater just blows cold air. If it isn't it could be that the heater control valve is not working and needs to be replaced, or on older cars a physical flap which alters the path of the air could be broken, or disconnected from the controls. Some vehicles have one or more "bleeder" valves on the thermostat housing and/or hose connections. Fix It Yourself with CarHop If the blower motor isn't working, if there is no sound and no air coming from the system, the blower motor may be defective. The coolant is housed in a … Heat in automobiles is supplied by hot coolant circulating through the engine. A blown fuse is a symptom not a cause. Certain specifications, prices and equipment data have been provided under license from Chrome Data Solutions ("Chrome Data"). There are many reasons your car's heater isn't working. Either the blower isn't working, in which case you may get warm air but not much of it, or it is blowing air but it may not be very hot. Maybe the fan is malfunctioning. To prevent the problem from reoccurring, the cooling system should be flushed and refilled with a fresh 50/50 mixture of antifreeze and water. Several things can potentially go wrong with automotive heaters because, much like a home heating system, there are many components working together to heat your car. But if your car heater blows cold air and you’ve checked both heater core hoses to make sure they’re hot, you likely have a bum blend door actuator. If a cooling system is full and there's still no hot air coming from the vents, there could be air trapped in the system. All Rights Reserved. Here is what to check if your heater or defroster isn't working: Coolant/Air lock - Did you top off the coolant as described above? Systems that simply don't work at all In this case, you're looking at a faulty blower motor, or an issue stopping power from reaching the blower motor. Car heater not working [closed] Ask Question Asked 7 years ago. Thermostat. On most vehicles built since 1970, vacuum operated heater control valves are normally open unless vacuum is applied. The link to our car repair article with more tips and tools mentioned in the video is here - http://blog.wiseautotools.com/car-heater-not-working-troubleshooting-how-to-fix-repair-tips/ A fuse blows when a circuit overloads to protect the wiring and other components against damage. The valves should then be closed when coolant starts to drip from them. The motor itself can be checked by using a pair of jumper wires. If a new fuse blows as soon as the blower is turned on, the heater circuit or motor may have a short that should be investigated. In order to fix this, you might have to prise open the heater box, or perhaps even lift a section of the dashboard to access the blower. Thermostat If the thermostat is jammed open causing the car to overcool, there may not be sufficient temperature in the coolant to provide sufficient hot air. Before I took it there, I had burned out the AC Compressor. Usually this will take a few minutes. If the cooling system has recently been worked on, a misrouted hose is a possibility. The system is very simple and rarely goes wrong. However the Vacuum fill system by FJC can be used to fill cooling systems and eliminates air being trapped by using vacuum and the coolant is drawn into the system. When a car heater doesn't work, the most common cause is low coolant. Cold air from the outside, or recirculated air from the inside, is directed either completely or partially through that heater core. If the switch is working, next check between the switch and the heater element. Want to improve this question? An open thermostat may be the problem, or one that is too cold for the system. If the heater isn't blowing any air, skip to the next section. Check the coolant level in the radiator to see if the radiator is full. If the air coming through isn’t hot, the heater core is probably clogged. If you notice your car isn’t getting as warm as you’d like, or the heater never actually kicks in, make sure to take your car … to the data presented here. On vehicles that lack these special bleeder valves, it may be necessary to temporarily loosen the heater outlet hose so air can bleed out as the system is filled. If the motor fails to spin, it should be replaced. If the heater does not … When troubleshooting to try and repair the car heater, check the coolant ONLY when the engine is cold. If that’s the case and you don’t get it fixed, you could wind up with a major … If your heater isn't working, the coolant level may be too low, the heater core could be clogged, a heater by-pass valve may not be opening, the doors in your hvac system may not be moving or if the thermostat is stuck open, it will cause a temporary lack of heat. Blower still does not work. 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