stvmcqueen

1994 Lexus ES 300 with hydraulically driven radiator fan motor

Same problem as previous post from Brando, "Strange problem...When driving about four hours straight I noticed that when pulling through a parking lot slowly that my radiator fan was increasing and decreasing in speed relative to throttle position."

Most of the answers to this thread said that they fan speed was normal to keep the engine at the right temperature. This is not a normal problem, my fan runs like a bat out of hell too. I recently replaced the fan thinking that the hydraulic motor had gone bad and that's why it made the high pitched whine during acceleration, but the new fan does the exact same thing. Mine begins running really high after driving it for about 15 minutes. No temperature problems. It usually begins after the engine will have already reached it's median temperature and will be holding steady. Seems like more of a time issue than the car getting to a certain temperature. When the fan is running really high my acceleration is terrible especially after stop lights or stop signs. I have to really stomp on the accelerator to get the car moving. The fan runs really high and seems to take a lot of the engines initial power. I'm thinking about replacing the temperature sensor of the whatever regulates the flow of power steering fluid throughout the system. Wondering if anyone has any advice for what the problem might be. Thanks everyone for their time.

CUMan

If the temperature gauge needle is not fluctuating up and down, it seems to me that the fan speed control system is doing its job properly.

The cooling fan has a control unit underneath the glove compartment. It monitors the coolant temperature and sends a signal to the power steering pump when more or less fan speed is needed. More fan speed is normally needed when the car is moving slowly or idling. Less fan speed is needed when the car is moving at a speed high enough to provide good air flow across the radiator. I think the change in fan speed would be more dependent upon the type of driving you are doing rather than the amount of time since starting the trip.

I could see where an increase in fan speed would put more load on the engine because of the power diverted to the power steering pump. But I wouldn't think this would be substantial enough to be very noticeable.

We have a 94 ES. I have never noticed any great decrease in power when the fan is running faster. But then, I don't even notice any increase in fan noise under different driving conditions. We have had the car for about 14 years, and I guess we are accustomed to the sounds.

stvmcqueen

I can hear the loud hum of the fan spinning even while driving for an extended period of time on the interstate. I thought the attraction to the electronically controlled radiator fan motor was that it would not draw power off the engine like an electric one might when the fan is moving faster. Does it really make sense that the fan speed should increase along with the engine speed without any kind of regulation? I would think the increase in fan speed would be a step by step increase holding steady at each level for a period of time. My fan speed just spins faster according to how fast the engine is moving. I can't believe this is a normal behavior for this vehicle when everyone is looking at me in a parking lot as I slowly touch the acceleration and my fan speeds up to a loud whine every time.

stvmcqueen

So really it just seems to me that whatever is supposed to regulate and keep the fan at a certain speed is not working correctly after the car gets heated up. It just gets to a point where there is a direct correlation between engine speed and fan speed. The fan speed should increase to a certain level and hold steady until it's necessary to increase again. My fan slows down when I'm slowing down to a stop sign and speeds up as I take off. Will anyone tell me that this isn't normal?

BadViper22

+1's all over the place.

stvmcqueen

Yes, I'm familiar with that quote, thanks. Very helpful. But if the engine is getting hotter then the fan motor should get up to a higher speed and maintain that speed. Not increase uncontrollably with the acceleration of the engine. I find it very had to believe that my lexus is supposed to sound like loud whining piece of ****.

keithsund

I had all my power steering hoses replaced for small leaks, now my fan is doing the same thing. The mechanic who cares for my car called lexus got no help from them. They feigned ignorance. If you have any system that involves a sensor and a regulating switch then you can expect failure eventually. The mechanic who took care of my car went directly to the fan speed controller and pulled off a vacuum line and that made a difference. On my 1993 ES300 it is located between the top of the engine and the firewall, about mid block. No too hard to access. When I have a final solution I will post w photos.

Brando

When I had this issue I found a red coolant sensor on the passenger side that was causing the issue. It had snapped in half but was still attached and was giving intermittent readings to the computer which was causing the crazy speeds of my fan. I pulled one off a wrecked car. Problem fixed!!


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