I have a 2005 Civic EX and was just wondering when I stop for short time (let say to pick up mail) and as soon as I drive again, I could hear some hissing/fan blowernoise from the engine compartment...sounds like if the system initializing or something like that..does anyone ever hear the same thing? The noise disappears when I drive and it will re-appear when I do the same thing (stop for short time and drive)

thanks.

 

That's the radiator cooling fan kicking in. There are two fans, one is driven off the a/c circuit and kicks in whenever the ac is on, to cool the condenser. The other is for the radiator is driving off the coolant temp sensor. When driving there is usually sufficient airflow through the radiator to cool the coolant, however when stopped there is no airflow through the radiator, allowing the coolant to heat up until it trips the circuit turning on the rad fan, this cools the coolant down and the fan turns off. This cycle repeats itself whenever the coolant temp gets hot enough.

 

thanks for the info.