fans
Thread Starter
Junior Member
Joined: Aug 2008
Posts: 36
Likes: 6
2015 s550 coupe
fans
are the two fans in front of the rad for a/c only? when do they go on...i had a bit of a fender bender and my horns were touching them..i just saw it today for the first time..i fixed them... i turned the a/c on but they didnt spin..it is 30 deg outside now so it will take awhile to heat it up to check them... im worried the motor burned beacuse of the horns.
fiddlyD
fiddlyD
Super Member
Joined: Apr 2007
Posts: 737
Likes: 38
From: Fort Worth, TX
2019 CLS450/ 2002 CLK55
I don't know for sure about MB. And anyone can definitely correct me if I'm wrong. However, on other cars that I've owned with twin fans.
The 'primary' fan will come on when your coolant temp reaches 'xxx' degrees. The 'secondary' fan comes on when your coolant reaches 'xxx' degrees plus 'xxx' degrees -OR- you turn the AC on.
So, if you get in your car and turn the AC on even without the car being at operating temperature = no fans.
If the car is up to operating temperature and kicks the primary on on its own and you turn the AC on = primary and secondary fans should kick on. (in fact, you should be able to watch first fan run and then 2nd kick in with AC).
Again, this is from past experience, but no necessarily with MB.
I can check what my car does if you want me to.
John
The 'primary' fan will come on when your coolant temp reaches 'xxx' degrees. The 'secondary' fan comes on when your coolant reaches 'xxx' degrees plus 'xxx' degrees -OR- you turn the AC on.
So, if you get in your car and turn the AC on even without the car being at operating temperature = no fans.
If the car is up to operating temperature and kicks the primary on on its own and you turn the AC on = primary and secondary fans should kick on. (in fact, you should be able to watch first fan run and then 2nd kick in with AC).
Again, this is from past experience, but no necessarily with MB.
I can check what my car does if you want me to.
John
Super Member
Joined: Feb 2008
Posts: 502
Likes: 3
From: Bay Area
02 clk 55, 13 GL 450
I cant say I have ever noticed mine run and never had a heating problem. I suppose they could run with the AC on and even though that would be effective, not necessary. Modern day clutch fans alone can handle the extra load of AC service. Aux fans are typically incorporated in low flow applications for engine heat. I.E. small grill area/stop and go traffic
