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mbsprinter
05-08-2015, 05:42 PM
I just replaced my condenser fan and I want to test it. Can someone tell me under what conditions it should be on? Every time I check it it's not running even with AC on, engine at operating temp, etc.

Dougflas
05-08-2015, 06:02 PM
If you're talking about the aux electric fan, it comes on when the high side reaches about 300 psi and runs until the high side drops to about 210 psi.

mbsprinter
05-08-2015, 06:46 PM
I'm talking about the electric fan that sits right in front of the AC condenser, behind the grille. Thanks for the info Dougflas but can you tell me how often it should run with the AC on?

Dougflas
05-08-2015, 09:31 PM
there is no set time. It will cycle on and off depending upon it's need. This depends upon the ambient temperature of the air in front of the condenser.

Jamescell
05-09-2015, 01:31 AM
If you unplug the high side pressure transducer the fan should kick on after a second or so.


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Aqua Puttana
05-09-2015, 01:49 AM
The electric fan operating is not directly referenced to ambient temperature. It is controlled as to engine coolant temperature and/or A/C system head pressure. A CAN bus communication fault may also cause the electric fan to operate.

The aux electric fan doesn't automatically come on all the time with the A/C on. It is controlled by a pressure/setting/sensor. 300 psi head pressure sticks in mind. That said, I don't know the designed pressure setting.

Don't expect the Aux Electric Fan to just come on because you switch on the A/C. The A/C needs to be working hard to get the head pressures up.

vic

Nothing wrong with your memory...
Quoted:
The radiator fan does not normally come on until the high side reaches a higher pressure, it is normal for the fan not to come on until the high side gets close to 300 psi.... If it is only reaching 200 psi, the radiator fan will not come on so that is one reason that I think that it may be low on refrigerant, This system is very sensitive to the amount of refrigerant in the system, it must be correct or the system will not function properly, if it is undercharged or overcharged it will not cool properly. Because of this, my first recommendation is to evacuate the system and recharge it with the proper amount of refrigerant from the label under the hood, If this is a factory front system it takes 1.9 lbs of R134, make sure that is the amount that is in there....

Steve

The aux. coolant fan is activated by refrigerant pressures above 290 psi
OR
by [engine] coolant temps above 221 degrees F.

Doktor A

As always, clicking on the blue arrow icon within any quote box will take you to the original post/thread.


My experience with my 2004 is that the aux electric fan only comes on when I'm towing my sailboat trailer and climbing hills. just having the A/C operating does not automatically fire up the electric fan. I've noticed that on my particular Sprinter the electric fan kicks on at around the 221F which Doktor A mentioned and cuts back off somewhere around 200F. That is using the OEM gauge scaling which is rough at best.

Dougflas
05-09-2015, 02:31 AM
<<The electric fan operating is not directly referenced to ambient temperature. It is controlled as to engine coolant temperature and/or A/C system head pressure. A CAN bus communication fault may also cause the electric fan to operate.>

When I stated that the ambient temp determines when the fan kicks on I consider that true. Head pressure is dependant upon the heat rejection of the condenser. If the ambient is low, the head pressure is also low so the fan will not activate until the head pressure gets to around 300 psi. When the head drops to around 225 psi, the fan will shut down. Colder weather will make the fan activate less often than hotter weather.

Many vehicles have the aux fan activate when the AC is turned on but the Sprinter does not operate that way. If you want to check the aux fan operation, block the condenser airflow to raise the head pressure.

morre
05-14-2015, 01:51 AM
if you want to check fan operation unplug temp sensor on a thermostat and turn key in a position 2, no need to start engine.