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Rx300 04 Ventilation Servo


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My wife's RX300 used to demist the front windscreen, especially on a cold morning, really well, but now it doesn't. There is no air coming from the vents at the bottom of the windscreen, even when the fan is at full blast. There used to be a noise like a motor trying to find a "home" position from behind the far right of the dashboard, but that seems to have stopped now. I believe the noise was from a servo that redirects the airflow; maybe it was sticking or something and now it's just given up trying.

The local dealers have quoted £700 to replace the servo, which, frankly, just isn't going to happen. They said to replace the servo requires taking out the entire dashboard. Does anybody know if that is true or not? I have a Haynes manual that says taking out the dashboard is probably best left to people with some experience, which is advice I'm happy to take. Can anybody recommend a garage that speaks fluent Lexus without charging a small fortune, preferably near Newcastle upon Tyne.

Thanks for reading.

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Hi there. This is correct in that the dash has to come out (assuming you have a mark II RX). Unable to recommend any garages but if it were me I'd go to lexus as they should be familiar with taking the dash out, but more importantly, at putting it back in properly so that it doesn't rattle. That said you could get a complete numpty working on your car even at lexus...... Good luck.

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I was quoted £299 from lexus sheffield to do the servo next to the drivers door window. I spoke to the garage where I bought the car (non lexus) and the guy had done one on his own car. he said it would take an hour and the dash didnt need to come out. I havent had it done as its none essential. He said the rest of the vents would need the dash out.... Certainly the main windscreen vent which is very much essential... You might save a couple of hundred £ at most, but it may not be done perfectly. Its a judgement call to trust a garage that say they can do it for a saving? or to pay the full lexus price... It needs doing regardless at this time of year. I got rid of my last car and got the RX 300 for this very same issue..... good luck

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  • 10 months later...

Forgive me for replying to my own question, but I thought my experience might help some poor unfortunate faced with the same problem.

The happy news is, it is possible to replace the mode servo without removing the whole dash, but it is still a challenge. You need to remove the scuff strip on the driver's door (just pull off, disconnect light connector), the central console small panel beside the parking brake pedal (two poppers), then the cover above the pedals (one bolt, one screw behind a cover, a few connectors to disconnect and the bonnet release catch to disconnect, all fairly easy). Then it gets a little harder.

Remove the knee air bag (disconnect the Battery -ve terminal, wait at least 90 seconds, undo four bolts, remove diagnostic socket, disconnect yellow cable from air bag by first lifting black clip from connector. handle gently).

Then remove Air Duct 2, the one that's blocking your view of everything. This is held on by one bolt and three claws. It's clearly designed to be installed, not removed, but the third claw, the one at the back, can be levered off with a thumb and then the duct pulls off towards you.

Next move the parking brake pedal out of the way. First disconnect the connector for the parking brake warning light. The pedal is secured by two nuts and one bolt. These are reasonably easy to get to with a long extension bar on a socket set. It's a bit of a wiggle to get the pedal off the two captive bolts that hold it on to the floor pan, but it is possible. Lay the pedal down as low as possible. To re-install, the nuts go on at 22Nm and the bolt at 24Nm torque.

With the parking brake pedal out of the way, it is not too difficult to get to the mode servo, but you'll still need a very small screwdriver. I invested in a Wera bit ratchet with bit check, which was a bit expensive, but it is a lovely bit of kit. You can buy the bit ratchet on its own (8001A) which is a lot cheaper, assuming you have a PH2 screwdriver bit already. This gives a very compact way to screw and unscrew in tight spaces and is just perfect for this job. The mode servo is held on by three cross-head screws, only two of which you can see, but it's reasonably easy to feel where the third one is.

As for repairing the servo itself, so far I've had limited success. The first time I just cleaned it up, as the grease from the gears had got onto the position sensor. This would have been a complete repair, had I done it as soon as the servo started continuously hunting for its correct position. But I didn't know then what the motor noise was and the continuous movement wore the carbon resistive track away rather badly. However, a good clean out and all seemed well. That lasted several months, maybe six, but the hunting started again just recently. So I removed it again with the intention of replacing it, but my curiosity got the better of me and I've tried painting the worn-out track segments with a graphite solution (a graphite lock lubricant from Maplin, which I had already). I doubt this will last long, as it seems very soft, but it is working for now and it seems criminal to throw away a whole servo just because a small portion of carbon track is worn away.

I'll try to get a replacement part at a sensible price. Meanwhile if anybody has any suggestions for painting on carbon tracks, I'm all ears. I'd love to fix this for free (well, except for a lot of my time and that Wera bit ratchet and bit check kit, that is). I hope this helps somebody.

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  • 3 years later...

I have similar problem. My mode servo started make noise. It's working now but have no idea how long. So, I'm going to prepare repair it. Currently collecting information how to get to the mode servo.

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