What's wrong with Ford Focus's warm air?
A 20 16 Changan Ford Focus sedan, with a mileage of about 53,000 km, an engine 1.6L and a five-speed manual transmission, was warned that the engine temperature was too high when the vehicle was driving on the expressway. The user asked the rescue vehicle to tow the vehicle to our factory for inspection and maintenance. Fault diagnosis: After the vehicle was towed to our factory, according to the user's description, the vehicle could not be lifted quickly after the water temperature was high. When the user leaves the car, 1 By the way, check whether the warm air is hot, because the warm air will be gone if the water temperature is high. After receiving the car, first check the coolant level. Within the normal range, connect the diagnostic instrument to read the vehicle fault code, and no fault storage is found. When the vehicle was parked (when the engine was cooled), it was found that with the increase of coolant temperature, the cooling fan also turned, and it was hot air and air conditioning warm air, and no obvious abnormality was found. The vehicle went out for a road test, and the situation described by the customer appeared after driving for about 2km. The instrument cluster shows "Engine temperature is too high, please stop safely". At this time, you can hear the sound of the cooling fan running at high speed, the warm air begins to cool down, and the pointer of the coolant thermometer fluctuates frequently from the middle line to the highest line. Then the pointer of the coolant thermometer stops at the highest position, and the fuel filler door does not respond, that is, the engine is in a torque limiting state to prevent the coolant temperature from further rising and damaging the engine. After getting off the bus, I found that the coolant pipe was hard, the upper pipe of the water tank was very hot and the lower pipe was very cold. After the flameout, wait for a while and unscrew the lid of the coolant pot. There is a lot of air in it. With the tense atmosphere in the car, the above situation will soon repeat itself. I consulted a friend before and got the message that the thermostat of this car is rarely damaged. In this case, you can replace a water pump first, because the car is driving close to 60000km, and the water pump needs to be timed. You can change the synchronous belt when changing the water pump. In the process of obtaining the customer's consent to replace the water pump and the synchronous belt, it was found that there were many sediments (or crystals, as shown in figure 1) on the water pump. Coolant looks relatively clean. Upon inquiry, the customer learned that the coolant was not replaced in this well, but it was replenished once this summer, and the amount was less than half a liter. After replacing the water pump, the car started and the fault remained.
Since sediment has been found on the water pump, are there any in the water tank and warm air box? Remove the upper and lower water pipes of the water tank and blow the water tank with compressed air. No obvious resistance was found and no deposits were blown out. However, when the heating pipe is removed and compressed air is used to blow the heating tank, the resistance is obvious, some deposits are blown out, and the resistance of the heating tank is also reduced a lot. After modification and debugging, it is still the alarm of coolant temperature, but the change is that there is still air conditioning warm air after the alarm. Because it takes a lot of time to replace the warm air tank, in order to eliminate the fault caused by the warm air tank, another water pipe was found to short the warm air tank (the original warm air pipe was removed, and another suitable water pipe was found, one end of which was connected to the warm air outlet pipe on the five-way valve, because the coolant flowing through the warm air tank returned to the kettle after passing through the oil radiator, and the other end was directly connected to the oil radiator), and the fault still existed. After repeated observation, it was found that the cooling fan was really hot air at first, but it was cold air soon, and then it turned to high-speed operation and could not stop.
(Photo/Text/Photo: Pacific Auto Network Q&A called Beast)