At what temperature should the auxillary fan turn on. The fan in my car does not turn on until the temperature is almost in the red. Is this normal or should the fan turn on before it gets so hot. Thank you in advance for any responses.

 

what is your car model? diffirent system on every car, and so is the value and switching components.
giving us the chassis number is a big thing.

 

chassis number WDB1240301A558117

engine number 103983 12 083319

I live in phoenix so I would rather have the fan turn on a little early then letting the engine get hot. thanks again

 

by the way, I read your post over in the e class forum about the thermostat could this be a problem? My radiator has been replaced recently and it runs cool when your driving. But if it sits in traffic it will start to get hot.

 

There is a temperature sensor switch that switches on the relay to the fan.
The switch comes with different temperature specifications.
I am using one that carries the inscription 72°C on it.
This is just an on-off switch unlike the one for the temperature guage.

 

AZ300e, most of the models should come on just before 90 or around 90.
All my cars have been about the same at that temp. My years are 93 to 99' 6 cylinder.

 

you must understand that the switching on of the auxilliary fan not only involves the coolant temperature but of the refrigerant pressure as well.

*the first stage (low speed) is being switched by a/c pressure sensor (it can be an a/c temperature sensor too, but high temperature means high pressure for freon) it's "ON" at 16 bar and "OFF" at 11 bar.

**the second stage (high speed) is being switched by coolant temperature sensor. "ON" at 107 degrees centigrade and "OFF" at 100 degrees centigrade.

OTHER THINGS THAT MIGHT HELP YOU:

>coolant thermostat start to open at 85-89 C
fully open at 102 C
(feel the lower hose if it's hot)
>>viscous fan coupling 96 - 104
you can easily check and feel this one.

please be careful in working on hot items...