Yesterday was pretty warm up this way. The wife and I were heading to an event requiring being somewhat "dressed". I decided to start the car and give the air conditioning some time to pre-cool the car. A couple of minutes later I could hear the fan (inside the engine compartment) running very fast and it was a bit loud. Is this normal? It was really cranking! It slowed down a bit while still idling and the interior cooled down nicely but it did leave an impression, so I thought I might ask the experienced owners if this was typical operation for the AC when the car is idling. The car is an '06 E350.
An idling engine has to produce its own airflow to control engine heat ... there's no airflow that occurs when the car is moving. The electric fans cycle on and off, and speed up and slow down, as necessary to aid the radiator in reducing the temperature of the cooling fluid circulating around the engine and through the radiator. At highway speeds, the fans may not cycle on at all, or perhaps only occasionally (depending on driving conditions) because the airflow is assisting the radiator in its function. Based on what you described, it appears your cooling system probably is working properly.
I know what you mean and I am half deaf. When my car was being picked up for routine service I asked the driver if this was normal and he said that it was common, I also asked the service writer if this was normal and he indicated that nothing was out of the ordinary. It is a heck of a racket though.
i have 03' e320 - w211 the fan (in the engine compartment) is constantly running at high speed, also it started yesterday after we got home from our trip. during our trip on the way home the ac was not functioning properly, the interior ac fan speed worked great, but the air was blowing cool, not ice cold as normal. when i got home i checked under the hood and noticed the ac lines were covered in ice. left the hood open so the ice would melted faster. it took a few minutes for the ice to melt ( live in florida ) and the ac began to blow cold air again but now the fan in the engine compartment is running at a high speed, constantly and will not slow down or stop. this has never happened before.
i can go out and start the car and within about 30 seconds, the engine fan kicks in on high and constantly runs. any ideas? thanks in advance for your response.
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