The heating system in the car is an important element of comfort, especially in the cold season. After all, it not only warms up the cabin to the desired temperature, but also protects against freezing and fogging of windows, as well as removes some heat from the engine. Therefore, when the cabin heater does not work – it is at least uncomfortable. We analyze why the heater in the car does not warm, what are the causes of possible malfunctions, and we will briefly tell you how to eliminate them.
The arrangement of the heating system
To understand why the heater does not warm the heater, first it is worthwhile to understand how the interior heater in the car is arranged in general.
In addition to the main radiator that cools the engine, in a modern passenger car there is another one – the heater radiator. It is smaller in size and is located behind the dashboard. Two pipes are connected to it – inlet and outlet, through which the coolant flows. It circulates through the cooling and heating system of the car with the help of a special pump (pump).
In the process of engine operation, heat exchange takes place. Antifreeze heats up, taking some of the heat from the engine, and flows into the radiators (main and heater). The heater fan blows cold air through the radiator honeycomb, and reverse heat exchange occurs – the radiator transfers heat to the air, and the air cools the heater.
Warm air blows into the passenger compartment, and cooled antifreeze returns to the engine to pick up excess heat again. This heating system is the most popular and efficient, although in some internal combustion engine cars (not to mention electric cars) it is supplemented by an electric air heater (tan).
The simplest configuration of the cooling system. On the right is the heater radiator with cabin fan
Low efficiency of the heater can be caused by many reasons. Let’s look at the most common ones.
Insufficient amount of coolant in the system
A banal lack of coolant (coolant) can cause the heater to blow warm, not hot air. Low antifreeze level leads to the formation of air plugs in the system, and the efficiency of the heater drops sharply.
Reasons why the coolant can leave the system:
- non-tightness of branch pipes;
- vaporization due to overheating;
- cylinder head gasket or heat exchanger malfunction.
How to fix the problem
To begin with, you need to find the expansion tank – a plastic reservoir in which coolant is poured. Unscrew the plug and top up the liquid above the MIN mark on the tank body. This should restore the performance of the heating system, at least for a while. It is also important to eliminate the heater air lock.
Important! Do not mix antifreeze of different brands or use tosol for refilling. Because of the different chemical composition can form a sediment that will remain on the engine parts and over time will reduce the performance of the motor.
To understand the cause of the lack of liquid, you need to find the place of leakage, carefully inspecting all parts of the cooling system. To do this is not very difficult – usually antifreeze leaves colored streaks on the parts. In case of leakage of any of the pipes, you need to tighten its clamps, and if this does not help – put a new pipe.
Antifreeze can get inside the cylinders, if the head gasket is damaged. In this case, the exhaust gases acquire a whitish color. In addition, because of such a malfunction, the engine can “boil” in harmless situations.
There is only one way out – to replace the gasket. The amount of work is large, it is quite complex, and the level of responsibility of the repairer is high. Therefore, if you have not had to disassemble the motor yourself before, it is better to contact the service.
Thermostat malfunction
Another reason why the heater in the car does not work is the failure of the thermostat. This is a device that performs the functions of a thermostat and is responsible for maintaining the temperature in the cooling system.
It has two circuits: small (bypassing the main radiator) and large. A classic thermostat consists of a brass cylinder filled with wax, a rod and two valves with a spring. When the cylinder heats up, the wax mixture expands and pushes the rod out, thereby opening a valve that allows fluid to flow through the large circle of the cooling system. The approximate temperature at which the valve begins to open is 82°C.
In modern cars, more and more often installed thermostats with electronic control, where the main sensor is a thermistor. With such a thermostat, the engine ECU can control the temperature more flexibly, but the dual circuit configuration is retained.
If the thermostat valve is jammed so that it always lets the fluid circulate in a large circle, the engine will warm up slowly. And with it the radiator of the heater, so it may seem that the heater in the car does not work.
How to fix the problem
To remove the thermostat, the first thing you need to do is to drain all the coolant. You can do this by removing the hose at the bottom of the radiator, and also by unscrewing the special plug on the cylinder block, if there is one. Next, we find the thermostat and remove it. Most often it is located on the upper branch of the main radiator, which goes to the engine. This unit is not repairable – you will need to put a new one, at the same time replacing all the seals.
Important! The work of the mechanical thermostat can be checked: it should be removed and lowered into boiling water. If the valve in it when heating opens, and after cooling is closed – the thermostat can not be changed and look for other reasons.
Pump Failure
Pump – another name for the pump, which provides circulation of antifreeze through the cooling system, whether it is a small or large circuit. A standard pump consists of an aluminum housing, pump shaft with impeller, bearings, gaskets and oil seals. There are also pumps with plastic housing or impeller. It is with the wear of the impeller can be associated with poor operation of the heater.
In simple words, the impeller is a disk connected to the blades, due to the movement of which the liquid is pumped through the cooling system. Due to prolonged interaction with antifreeze or other coolants, the impeller wears out and slows down the movement of liquid inside the system. Especially spoil it low-quality antifreeze, which because of its chemical composition literally corrode the impeller. In addition, it can turn on the shaft and stop rotating properly.
How to fix the problem
Replacing one impeller is not the best idea. And it is practically unrealizable in modern pumps, the design of which does not involve disassembly. The coolant passes through the entire pump and interacts with each of its elements. Therefore, it is worth replacing the old pump completely with a new one.
Each car has a different design, but the pump is usually located outside the engine and is driven from the crankshaft either by a timing belt (or even a chain) of the timing belt, or by a single belt with the generator. In any case, replacing the pump is not the easiest operation, requiring draining all the antifreeze and then filling the system again. Therefore, if you lack auto repair skills, it is better to contact a car service. And when replacing independently, do not forget to thoroughly clean and degrease all mating surfaces, as well as replace the gaskets with new ones.
The clogging of the radiator heater
Why does the heater warms badly, if everything is in order with the pump? The matter may be in the clog inside the heater itself. Heater radiator – a rectangular-shaped part consisting of a pair of tanks (more often plastic), connecting them thin metal tubes through which the heated coolant flows, and plates between them (the so-called “honeycomb”).
If several tubes are clogged (for example, by scale when using low-quality antifreeze or ordinary water), part of the radiator remains without heating liquid. Therefore, the air from the heater is not hot enough.
By the way, the space in the honeycomb can also be clogged. Some drivers do not see the point in the cabin filter and save on it. As a result, the heater radiator quickly clogs from the outside. Air passes through it with great difficulty.
How to fix the problem
To begin with, you need to check the pipes of the heating system, leading from the motor to the cabin. And if one is barely warm, and the other is hot, then the matter is in the clogging of the radiator. Read more about how to wash the radiator of the heater with your own hands here.
What to do if the honeycomb is clogged? Here without removing the heater and mechanical cleaning can not do without it.
Clogged cabin filter
Another reason why the heater blows badly in the car is a dirty filter of the climate system. It is a consumable element made of paper or synthetic fibers. The main task of the filter is to protect the cabin from dust, insects or leaves.
If the cabin filter is heavily clogged, it provides additional resistance to the air flow. And the less it passes through the heater radiator, the colder it is in the cabin.
How to fix the problem
Depending on the design of the car, the filter can be installed both inside the body (under the dashboard or behind the glove compartment) and under the hood. If you have noticed a weak air flow from the heater, you can try to change the filter yourself – usually it is not difficult. As a rule, replacement is recommended once in 10000-15000 km (or more often, if you drive a lot on dusty roads).
Heater fan malfunction
If the heater in the car does not warm up, the reasons for this can also be associated with the cabin fan. It is he who runs the air through the radiator of the heater.
The main faults are as follows:
- breakdown of the electric motor of the fan;
- clogging or damage to the fan blades;
- failure of the electrical control system of the fan.
How to fix the problem
If the heater blows weakly, then, perhaps, blowing and cleaning the fan impeller blades will help. When when the heater is working, the cabin is filled not so much with heat as with noise, it is necessary to replace the brushes and/or bearings in the fan. If the heater stopped blowing hot air at all, then the heater motor must be replaced in its entirety. In both cases, you will need the help of an experienced auto electrician.
Totals
- To understand why the heater does not work, you need to conduct the simplest diagnostics and determine to which item from our list refers to your case.
- Some problems can be solved by yourself: for example, replace the cabin filter or top up the antifreeze in the system.
- There are complex malfunctions: a punctured cylinder-head gasket, a broken pump or thermostat. With such a thing it is better to address in service. Yes, and operate the car with them, most likely, will not work even in the warm season.
- It is not worth ignoring the symptoms of problems with the heating system: after all, it is part of the cooling system, which means that difficulties may arise with the heat removal from the engine.