As usual when the engine heats up after driving for a while hot air starts coming through. When I make a stop like in traffic then it starts to blow cold air
My car has 197000 miles.
My car has an automatic transmission.
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Jeff Engstrom
The lack of heat being generated by your system may indicate a clogged heater core. The [heater core]((//www.yourmechanic.com/services/heater-is-not-working-inspection) is a small radiator like unit that circulates the hot coolant from the engine through the heater core which then uses this warm coolant to heat the inside of the car with the help of the blower motor that blows the warm air through the vents inside the car. The other possibility is that the thermostat may not be allowing the engine to reach a normal operating temperature and since the engine’s warm coolant is the essential source of the heater core supplying heat to the inside of the vehicle, this can impact the warmth of the heat inside the vehicle. I would suggest having an expert from YourMechanic come to your location to diagnose your heating system.
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There are many car issues, which can easily infuriate vehicle owners. For example, a typical situation can include the car heater suddenly blowing out cold air instead of heat during winters. Such a situation can make it hard for you to drive to the office and back during the chilling winters. However, at the same time, there are different reasons why your car’s heats get cold when idling. Among these can be a leaky coolant or the direction of the air from the blower among others. Let us find out, which one is the culprit.
Know Here Why Your Car’s Heats Get Cold When Idling
You should know that there are different reasons, which can lead to a situation like this when the car heater does not blow hot air, but only cold air. As stated above, you are either dealing with a leaky coolant issue, air direction, or some other problem. We recommend you browse online to know the best maintenance tips for your car heating system. Given below are the three reasons why your car heater system suddenly starts blowing cold air even in winters.
1. Insufficient Coolant
The car coolant comprises of 50% antifreeze and 50% water. It helps keep the car engine cool, especially during peak months of summers. When you start the car heater during winters, the coolant travels through the engine to the heater core and provides warm air. You might feel cool air during the initial start of the heater, as the engine needs to warm up for the coolant to provide heat to the interior of your car.
However, in case, the air blowing out continues to be cool, check the coolant level. It is the first reason why car’s heats get cold when idling, as the car would not send less coolant would to the heater core to create warm air.
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2. Broken/Clogged Car Heater Controls
At times, the control buttons for the car heater might stop working. If the coolant level in your car is ok, and there is no issue with the heater core, you need to replace the buttons. The heater control valve is located under the car hood and controls the heat inside the car. If the piece does not work right, then it is a reason why your car might blow out cool air inside and not warm.
3. Water Leak
The last thing leading to this issue with the car heater includes a water leak. Make sure to check the hoses, radiator, and water pump for any damage. In case, any of these parts malfunctions, then the car heater would not function to its full capacity. We recommend that you connect with a reputed car expert to know about resolving this issue at the earliest.
Summary
Hence, we hope that this blog provided you with the necessary information about why your car’s heats get cold when idling in details. You can also browse online to know the best way to resolve this issue. Besides, consulting a car expert can help keep the car heater running during winters without any hassle.
A common problem that arises when driving in winter is that the air blown when the engine is idling becomes cold. There are a few reasons why the car’s heater gets cold at idle, which I will describe below.
If your car’s heater does not heat enough not only at idle, you could check the common reasons why the heater does not work or has problems with heating.
Related to that article the reasons why the heater blows cold air at idle are somehow similar with small differences.
5 reasons why the car’s heater blows cold air when the engine is idling
There are five main causes why the heater is cold at idle.
The low coolant level in the expansion tank
A low coolant level in the tank represents the main reason why you don’t have hot air in the cabin, it is not just related to when the engine is idling, however, this can be the reason why your heater blows cold air at idle.
Completing the coolant level with the same type of coolant represents an easy and quick fix. Also, if you see that coolant drops constantly without any signs of liquid leaks, check the radiator cap or the expansion tank cap.
You should not neglect this symptom because things can get serious and harmful to your engine. If the coolant has not been changed for a long time and/or is in poor condition, then it is better to replace it with a new one, the same brand, or with one that your engine needs, so it’s better to check the car manual.
A bad or failing water pump
This part is responsible for the circulation of coolant through the cooling system, and when the rotor is not able to create sufficient flow, the heater blows cold air when the car is idling, and when the car is moving it may be slightly warmer. If the pump is responsible, then it needs to be changed to a new one.
A dirty or clogged heater radiator
The heater’s radiator clogs over time making it harder for the coolant to pass through its bearings, leading to slightly warm air or completely cold air blown at idle. You can try cleaning the radiator and check if a crack has not been created where the liquid can come out or air can enter.
Usually, cleaning the heater’s radiator has a positive effect on the efficiency of the heater, including at idle speed.
A bad or worn thermostat
When the thermostat rod is jammed in the open position this can mean cold air blown when the engine is idling. If the coolant is initially circulated in the “big circle” in a cold engine, it will only be able to warm up after a long time of driving the car, or you will need to spend a lot of time warming up when the engine is idling.
Problems with the climate control system
Especially on newer car models, this system can sometimes have software issues, which leads to cold air blown by the car’s heater at idle. Problems can be associated with improper configuration of a particular system, or with software or hardware problems of climate control.
Checking its operation depends on the specific car make and model and the type of system. These steps are usually described in the car manual. If there is such information, you can check it yourself. Otherwise, it is better to seek help from a car workshop.
Air in the cooling system
The presence of air in the cooling system can be due to improper replacement of the coolant, depressurization of individual pipes or their connection point, malfunction of the air valve, problems in the pump operation, or because of a damaged cylinder head gasket.
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.
The coolant supply is blocked
If the heater has a tap for supplying coolant to the radiator, then this is closed or jammed because of rust. This type of heater is present, in most cases, on older cars and the simplest solution is to open the tap. When using more water than the coolant, rust will form which jams the tap.
Conclusion
If the car’s heater is blowing cold air at idle, you should first check the coolant level, and its condition, completing the coolant level is the easiest way but not always the best way to fix this issue. Next, you need to check the water pump, thermostat, heater’s radiator, heater tap, and the presence of air in the cooling system.
You should remember that a poorly functioning heater, in any case, indicates a problem in the engine cooling system, and driving a car with these problems can lead to bigger problems and costly repairs in the future, so it’s safe to inspect the problem as soon as possible to avoid bigger issues.
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