What controls the radiator fans?? - Toyota Nation Forum : Toyota Car and Truck Forums

KS_Hicks · 06-15-2005, 07:49 PM

Hi, I'm new to Toyota Nation. I don't really know if this is a problem, but I want to ask anyway. I have a 1990 Lexus ES250 and my dual fans don't turn on when they are supposed to. What I mean is when I turn the key to ACC or to START both of my fans automatically come on. I know one is supposed to come on when the air conditioning is on and the other is supposed to turn on when the engine is a certain temp. They both come on at the same time whether hot or cold and they stay running until the car is turned off. I don't know if I have a problem, but I really don't want to burn out the motors on these fans. Could it be a relay, temp. switch, coolant temp. sensor or what?? Please help!!!!!!! Thanks!!

BlueFusion6851 · 06-17-2005, 12:19 PM

on my car (camry) the fans come on when the engine is warm, and when the air is on, your problems may be hydralicially (sp) related... take it to a radiator place or dealership and have them troubleshoot

KS_Hicks · 06-26-2005, 12:21 AM

I don't even know where to start looking. Please help!!

***Tercel GTS*** · 06-26-2005, 01:44 AM

Take it to a shop that knows what they are doing. That's an expensive high tech car you have and easy to create VERY costly repairs.

jhbhatia · 06-28-2005, 12:37 PM

I think older ES models had fans coming on when on accessory mode! (i've asked this on clublexus as well, and no one replied to my q)

KS_Hicks · 06-29-2005, 10:37 PM

So when the car is on or running, the fans are naturally going to run all the time?? Both fans even though the a/c is off?? This isn't like other vehicles whose fans come on when the temperature is right or if the a/c is running. So I might not have a problem at all??

Cyorke · 06-29-2005, 11:01 PM

It could be any number of things from realys to coolant temp sensor, to ac switches. Typically the fans will only come on when the car is at a designated temp or like you said when the a/c is turned on. Sounds like you need to have it checked out. I shouldnt be a hydraulic problem because the car has to be running for the P/S pump to run the fan like it does on a Gen 3 camry.

jhbhatia · 06-30-2005, 11:53 AM

I went thru the same questions, and all relays, thermostar, waterpump, everything checked out fine. I didn't get a clear answer, i've since added close to 50K miles since i first asked that question two years ago!

KS_Hicks · 07-02-2005, 02:14 AM

Well the thing is, is that I have in the Air Force and I am moving to Germany and I am shipping the car in about 3 days. If its not a problem then cool, but I do not want to burn out the motors on those fans cause I know they don't come cheap. By the way, how many coolant temp switches are there on this model and year??

mars7 · 07-16-2005, 08:24 PM

I just purchased a 1998 ES300 recently and have a similar issue. When the car is started up and idling neither fan runs. If I turn on the AC then both fans run. I let the engine idle for a while to warm it up and neither fan runs. Is this normal or is there a problem? If it is normal what triggers the fans to run without the AC running?

lexusmech · 07-18-2005, 01:00 AM

You might have a stuck relay. I don't know for sure on the ES250 (I have one) but on my Mazda, if you lose ground on a sensor, the fans come on automaticly as a default mode. Since the A/C fan is on too, maybe the switch for the A/C is stuck and/or lost ground. Would have to look at the schematics.