I've noticed that when I turn the A/C off (push a/c button and red light extinguishes) and continue driving, a very discernible moaning sound begins. If I activate the A/C, the moaning stops. What causes that sound?


Also, if I turn the a/c off and then turn the engine off, when I restart the engine, air conditioned air seems to be expelled for 5-10 minutes or so.
In my previous cars, when I turned the A/C off, the system ceased operating immediately and no moans were ever heard.


What am I overlooking here?


relinuca

 

A/C behavior-'09 E350 Quote--I've noticed that when I turn the A/C off (push a/c button and red light extinguishes) and continue driving, a very discernible moaning sound begins. If I activate the A/C, the moaning stops. What causes that sound?--Unquote


Pay more attention to your girlfriend!!

 

Can't say for sure - not having head under your hood, but when you turn AC off during driving, the computer will increase fan speed and divert air flow to different ducts, what comes with sound change.
Then by pushing the button off you are not cutting the whole system off. You are giving to computer a signal about your wish and computer does what it feels like. Talk about artificial intelligence.
That might be duct drying program that keeps air flow for some time.