[briggsrepair]

04 EX, 4 cyl.

I know the driver's side fan is for "radiator" and
passenger side is for "a/c".

Can someone pls explain what
causes both fans (or each individual fan)
to come on? (e.g.: turning a/c on, temp rising, etc.)

Thanks.

 

[CarlR33]

Page 2 will explain the fan operation of ac. The engine radiator is same principle only for the motor cooling.

http://autorepair.about.com/od/glossary/a/howitworks_ac.htm

 

[Drew03Accord]

http://autos.yahoo.com/maintain/repairqa/fluids_heat_air_conditioning/ques021_2.html

Fan Operation

At highway speeds, there is usually enough airflow through the radiator that a fan isn't needed. So the fan usually only operates when the vehicle is sitting in traffic or driving at slower speeds.

On older applications, the electric fan is controlled by a temperature switch located in the radiator or engine. When the temperature of the coolant exceeds the switch's rating (typically 195 to 235 degrees F), the switch closes and energizes a relay that supplies voltage to run the fan. The fan then continues to run until the coolant temperature drops back below the opening point of the switch. Most electric fans are also wired to come on when the A/C is on. Many vehicles also have a separate fan for the A/C condenser (dual fan systems). One or both fans come on when the A/C is on.

In newer vehicles with computerized engine controls, fan operation is regulated by the engine control module. Input from the coolant sensor, and in many cases the vehicle speed sensor too, is used to determine when the fan needs to be on.

CAUTION: Many electric fans are wired to come on anytime the engine is above a certain temperature, regardless of whether the engine is running or not. This means the fan may come on after the engine has been shut off. So keep your fingers away from the fan at all times unless the battery or fan motor wires have been disconnected.
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Aftermarket adjustable fan switches. You tell it how hot.

http://www.etrailer.com/dept-pg-Radiator_Fans.aspx

 

[briggsrepair]

Let me rephrase my question, three ways pls.

- In what scenario would only the a/c fan come on (passengers side)?

- In what scenario would only the radiator fan come on (driver side)?

- In what scenario would BOTH fans comes on?


Thanks all

 

[CarlR33]

- In what scenario would only the a/c fan come on (passengers side)? I doubt that scenario and if it was would be at highway speed.
- In what scenario would only the radiator fan come on (driver side)? coolant past operating temp trips fan without ac running.
- In what scenario would BOTH fans comes on? vehicle is at idle with ac on. I just checked this one by opening the hood at idle with ac on.