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i have Lexus RX 330 2005.

I noticed my Radiator/Condenser cooling fans operate only in "Low Speed" Mode in all 4 scenarios below. < Refer Attachment >

a) Engine coolant temperature 90°C (194 °F) or below - > Rotate (Low speed)
b) Engine coolant temperature 95 °C (203 °F) or above -> Rotate (High speed)
c) A/C Refrigerant pressure is less than 1,520 kPa (15.5 kgf/cm2, 220 psi) -> Rotate (Low speed)
d) A/C Refrigerant pressure is 1,520 kPa (15.5 kgf/cm2, 220 psi) or above -> Rotate (High speed)

I already checked below.

- Removed fan connectors from fan control module & directly wired fan motors to battery. Both fans rotate in high speed. -> No issue with fan motors

- Removed and re-plugged A/C pressure sensor socket. A/C compressor cut off happens in normal fashion.

- Test control pulse to fan control module. ( i.e. " Small Green wire " ). It gives 1.7v~ 2.0v for radiator coolant temp triggers , 2.5v for Air Con triggers

Any clue on whats wrong here ... Is it due to faulty fan control module ?

Do anyone have 2004 ~ 2009 RX 330 / 350 fan control wiring diagram ?






Fan Speed.png

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My take is this, go by your temperature gauge. If it does not rise above normal during warm weather and stop and go driving, then why worry about fan speed? If u feel the engine is running hot, then it will need to be diagnosed by a dealer with the proper equipment. 

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but it has impact on AC high pressure side. My high pressure side ac hose got leaked near compressure due to higher temp. So ac condenser won't cool down gas efficiently. Specially when vehicle is parked and in idle mode with AC switched on. 

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  • 4 months later...

I have the same problem. The fans do not run when sitting with engine idle. This condition fails to keep the AC running cool. Interested in knowing what may be causing this.

2006 RX330 Canada model.

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  • 4 years later...

Causes me to wonder if there are cases of over pinched wires at connection points causing excess resistance to the coil in the relay that controls when the fan does what it does. 

Over pinched wires are fairly common in several manufacturers vehicles including Toyota and Lexus. 

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A little back story, I bought the rx330 a few weeks ago with the issue of both cooling fans that run continuously on full blast as long as the car runs. Doesn't matter if AC is on or off. Found out that the issue was the cooling fan module. After replacement the fans only comes on after driving and letting it idle for awhile also with the AC running. The problem I now have is the fans would never kick into high speed it should kick in at 203°f . Car runs great its not overheating. The temperature gauge is spot on the middle. Just ordered a scanner with live data to make sure the gauge is reading correctly. I'll keep you guys updated if I find anything else. Sorry for the double post from earlier.

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Has the outdoor air been hot since you started having the issue? As in if nice cool air is being sucked across the cooling fins the sensors may not call for high speed fans. 

Just a thought. 

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Out side temperature is high 80s to mid 90°f just got the car not long ago. I haven't a clue how Lexus cooling fan operate. Been driving a rsx type s for the past 12 years. 

Fingers crossed it's just not hot enough to trigger the high-speed.

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Well, I suppose upper 80's to lower 90's could trigger a high speed. In my Ford work truck for example during a mid atlantic winter the fan does not run very fast when the truck idles but does run briefly at times.  In spring I hear it running on days like you described, 80's and low 90's but that time of year the humidity it still lower than it is in the summer. It runs more but not wide open. 

In summer when it's 80 degrees at 6am and humidity is thick the nice lady at the Hardees drive through says "can you speak up there's something loud drowning out your voice?" ……that would be the cooling fan running wide open. 

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The most likely scenario that would result in the fans kicking in at high speed is during lengthy stop & go driving in high traffic conditions during high ambient temperatures.
Have you done this?

After driving in these conditions and after arriving home, let your vehicle idle for 5 minutes or so. I would think that the trigger temp would be exceeded and the high speed fans would be energized.

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30 minutes at most, haven't had the chance to drive much. I would say low stop and go traffic. Temperatures are in the low 90°f. I left the car idleing for 5-10 minutes still no high speed. Going to monitor coolant temperature when my scanner arrived today.

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Took a ride with the blue driver OBD2. Drove on the freeway for a few miles coolant temperature stay below 187°f.

Took the off ramp drove for a few more mile with moderate stop and go traffic. Temperature rise to 205°f. Still didn't hear high speed fans coming on. Once moving temps drop to 190°f. Outside temperature was 80°f

I Pulled over and have the car idle, after a minute the temperature rise to 208°f and drop to 185°f when cooling fan (low) came on. High speed still did not came on. 

Is this normal? Any RX owners with this issues? Thanks in advance

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Sounds like fans are getting it done without having to turn on high. 

Normal operating range is 195 to 220. If it goes to 225, then you should be concerned as 230 is when it begins to be in "over heated" territory. 

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