I was wondering, when driving 65mph on the Freeway; since the electric fan automatically comes on when you turn on the Air Conditioning doesn't that waste energy since the fan isn't needed?

 

i dont think it comes on with the AC automatically unless you are under 35 mph. even if it did come on it would not pull that many amps, if any, because it is spinning freely

 

If you start the engine and turn on the AC, the fan comes on automatically by the ECM. I just wanted to know if the electric fan would be canceled out by the speed of the 65mph air flow or have any negative affects on the fan motor.

 

Well, thats a good question. Anyone know the answer ???

Auggie

 

Turning the A/C on grounds a lead activating the fan relay in my single fan '92 TBI Firebird, it's completely controlled by that relay activated by a tempreture switch in the head or turning the A/C on. I'm not sure how the TPI or Dual fan cars are setup.

R

 

i have dealt with electric motors before, and if not put under a load they wont draw that many amps. it doesnt hurt the motor to be be in a low load situation

 

Well, OK that answers one question but what about the other 65mph question?? Anyone ??

Auggie

 

I ordered a Perma Cool electric fan that flows 2950 cfm of air. Now, if the fan was on and I put a 65 mph or higher blast of air towards it, wouldn't that make the fan slow down and work harder to maintain the 2950 cfm of air flow which in turn would make the fan draw more amps because of more drag?

 

or, if ur going 65 MPH, more then likely ur getting more air flow then those fans will ever be able to pull through by themselves. so therefore it would make sense for the ECM to cut them off at a certain speed. kinda like a mechanical fan

 

It sounds like you are thinking that the fan is blowing air forwards through the radiator. This would be opposite to the airflow when moving, but actually the fan is PULLING air through the radiator in the same direction as the airflow. Therefore the fan is not working against the flow. If the fan was slowed too much, for any reason, it would burn out.

PS. This is why the air dam is needed. It scoops air from below and channels it through the radiator. Without the dam, the suction of the airflow below the car would try to pull air forwards through the radiator. This is a reason why cars w/o the dam overheat.

 

That's what I was asking. If you have a Greater amount of airflow from highway speeds than the fan is creating then, that would put more strain on the fan motor since it's working against the higher airflow. That's why some cars have a Clutch fan so when there is sufficient airflow the Clutch fan just Slips. Try this, get two portable electric fans of the same size, put one on a slow speed facing like a puller fan then take the other fan and facing it the same way directly in front of the first fan and turn it on the high speed setting. The first fan since it is on the slow setting is going to slow down because of the higher air speed of the second fan which would cause it to draw more amps.

 

Yes, that's true, but the fan isn't fighting the 65 mph airflow, it's helping it, as long as the fan is pulling air through the radiator in a front to back direction. The air dam also pushes air through in the same direction. So all airflows go through the radiator in the same front to back direction.

 

but since the fan's aren't on at 65 MPH

 

If you were going fast enough, the air blowing through the fan could cause the fan to spin faster than normal. That's not a problem as the electric motor will just use less and less amps. If the air spun it fast enough it might put a charge into the battery A mechanical fan clutch doesn't kick out when sufficient air flow exists. A fan clutch is either thermal(kick on when the temp gets high enough) or by rpm. At higher rpms the clutch kicks out. Most are thermal.