gettoki

Thank you so much for sharing diagram. I got my 2010 RX checked by shop not Lexus dealer showing 3.78 V when OFF. The have charged gas and fixed leak. After reading your post it seems replacing flow sensor is the one I can use. Can you please share flow sensor part# you have ordered from eBay? or is it possible to buy booster circuit part from eBay. Again thanks in advance for your time. They didn't pull error code. Do I need to recharge system after flow sensor is replaced? Booster circuit won't need to recharge system from what I have understood so far. Much appreciated.

tn7con

The original AC compressor for 2010 RX350 is part# TSB19C. Go to eBay and search for "AC flow sensor RX350 TSB19C" and you should see several hits. The flow sensor is held in place by a horse shoe shape compressed ring. No need to recharge the system when replacing the flow sensor. Good luck.

gettoki

Will be trying this week replacing the old flow sensor with new one from eBay as shop (not Lexus dealer) won’t try any booster circuit. They are charging 4.5 hours labour $275 + refrigerant charge $50. Hopefully will fix this issue as shop is strongly recommending changing compressor with after market one. But will stick to flow sensor change for now. Shop says they need to take out compressor to change flow sensor. Nothing wrong with compressor as it came on during diagnostics when engaged manually. If anyone can confirm replacing flow sensor involves taking out compressor. Also since I’m paying for 4.5 hours labour, should I go new aftermarket compressor just in case eBay sensor fails or doesn’t work. Thanks in advance.

gettoki

Hi Tn7con!!

I tried new flow sensor from eBay, but didn’t work. If possible to design new booster circuit for me, can pay for it. As I don’t want to go for Lexus dealer route of new compressor and magnetic clutch $1889+$650+$350 +%13 taxes extra. I’m in Toronto. AC compressor comes in when engaged manually, error code B 1479 low voltage issue. Let me know if doable. Thanks

tn7con

What's the flow sensor return voltage after installing the flow sensor that you got from Ebay? The last person who replaced the flow sensor said to clean the flow sensor area thoroughly in order for it to work .... perhaps you would need to inspect the flow sensor area again ... all the design was already shared in this thread, the circuit is simple to build ... installing it takes a little challenge due to limited space around the connector to patch the flow sensor booster circuit. Do it at your own risk ...

Paultergei

Thanks to all in the above threads for sharing information. It saved me $2000 in not having to get the AC compressor of my 2011 Sienna SLE replaced. I am writing this to share my experience and information of how I was able to overcome a number of obstacles to change out the flow sensor without having to remove any substantial parts from my Sienna. That is, I was able to change out the flow sensor while the AC compressor and other parts (except connectors) remained in place in the car.

I know that this is a Lexus forum. I decided to post this on this Lexus forum because I think that the initial knowledge for solving my AC problem emanated from a Lexus forum, and I feel that maybe Lexus owners might be able to apply some of the knowledge below to fix the AC on their Lexus vehicles.

Although it took me a couple of weeks to figure out and overcome the obstacles, now that they are figured out, I think any adept weekend mechanic with the knowledge below can easily change out the flow sensor in a couple of hours (instead of weeks). I offer no guarantees that this will work for you, and I am not responsible for any damage that you might cause. I am just sharing knowledge, and any risk that you take is your own.

Other posts in this thread have good pictures of the flow sensor mounted on the AC compressor. I found that if I opened the hood of my Sienna and looked straight down at a position in front of the passenger seat. I could see the flow sensor mounted on the AC (just below the alternator).

The first and main obstacle at getting at the flow sensor is space. That is, there is tight spacing between the cooling fan shroud and the engine. I did not want the burden of removing the cooling fan or radiator, as my car had to remain functional while I worked on the AC. I have large hands, so it was very difficult to reach down into the space and have any substantial hand or finger movement. It was difficult to hold a tool in that space, and just about impossible to be able to manipulate that tool very much. There is an alternator connector snapped on right above the sensor mounting hole, and I found that if I unplugged that alternator connector, that gained a little more freedom to move my hands and fingers. If you do temporarily unplug the alternator sensor, do remember to plug it in again before starting your vehicle as I am not sure if damage would occur to the alternator if it is operated unplugged.

The second and also a main obstacle is that the flow sensor mounting is not flat or perpendicular to spacing mentioned above, but instead is mounted on a slant sloping from the engine side downward toward the front of the car. Because of the slant, you cannot apply any tool directly (i.e., perpendicularly) to the sensor mounting surface. The spacing between the cooling fan shroud and the engine is too short to allow you to apply any but the smallest tools perpendicularly to the sensor mounting surface. That is, there is not enough space to slant the tools so that the tool slant matches the slant of the sensor mounting surface.

The first thing that you should do in attempting to change out the flow sensor, is to go on-line and purchase an after-market flow sensor. Toyota does not sell the flow sensor by itself, so you must purchase one from a secondary source. I just went on Ebay and purchased one from a seller having a significant number of reviews, while still maintaining a near perfect review score. The sensors available appeared to range in price from $30-$50. The one I purchased cost about $40. I will take several days to get the new sensor, unless you pay extra for overnighting.

The next thing to do, is to get the old sensor removed. First, you have to remove a snap ring retainer. I was able to do it pretty easily by reaching down into the tight access space with an “L-shaped” pick tool, and work the snap ring out of its groove. There is a significant risk that the snap ring might fly or fall off, never to be found again, so you might want to buy a snap ring assortment to have a replacement snap ring on hand if needed. To determine the size of the snap ring needed, just hold the new snap rings up to the round part of your new flow sensor and pick a snap ring which is slightly larger than the round part.

Once the snap ring is removed, I found my old flow sensor impossible to remove without destroying it. That is, with hindsight of having done it, I think two things are working against having you remove the old flow sensor easily or in one piece. First is, I think that these sensors are not molded with precision, such that the molded case’s roundness does NOT closely match the roundness of the sensor mounting hole. My impression is that these sensors are forced into the sensor mounting hole with some type of pressure or hammering. The second thing is that white oxide built up around the sensor appeared to be gluing it in place. Long story short, the only way I found that I could get the old sensor out was to use a very long flat edge screw driver and hammer from above to crack up the old sensor into pieces and let it fall out of the slanted sensor mounting surface. If you do this, do it slowly and carefully so as not to pierce the AC compressor body, and not to damage the sensor mounting surface or the snap ring groove. Even doing it carefully, it did not take me long to break up the old sensor. Interestingly, most of the sensor part is resin, and inside, there is only a small three-pronged integrated circuit (IC) device which looks like a transistor.

Once the old sensor is removed, most likely you will see that there is a significant amount of white oxide built up within the sensor mounting hole. That is, the white oxide forms mostly under the sensor. I think that the formation of this white oxide over time might cause the failure of the sensor to work properly. For example, it might cause the sensor to be spaced too far from the sensor mounting surface, or the oxide itself might somehow interfere with the sensor being able to read properly. In any event, the white oxide has to be removed somehow. I tried many tools, but found it impossible to be able to apply any tool perpendicularly to the sensor mounting surface, or if I did apply a tool perpendicularly, I found that there was no ability to move my hands or fingers in the tight access space to be able to effectively remove any substantial amount of oxide. It took me a couple of weeks to figure it out. I solved the problem by taking a drill, mounting a long (e.g., two foot) screwdriver bit holder into the drill, then using silver aluminum foil tape to tape one end of a 2-3 inch length of coarse steel wool to the bit holder end of the bit holder. Then when I applied the bit holder end into the sensor mounting hole and turned on the drill, the steel wool wrapped itself around the bit holder end and conformed itself somewhat to the size and slant of the sensor mounting hole. The rotating steel wool did a pretty good job of removing almost all of the white oxide from the mounting hole. The only white oxide left was around the edges of the hole where the steel wool could not squeeze itself into the corners of the hole. After the steel wool treatment, I found that I could use my hands within the access space to use an “L-shaped” pic tool to scrape off the remainder of the white oxide from the corners. Result was a pretty clean hole.

The next problem is getting the replacement sensor into the mounting hole. I found that I had enough manipulation with my hands and fingers to get the sensor started into the mounting hole. But the problem encountered was that the sensor did NOT easily slide down into the mounting hole. As mentioned above, I think that these sensors are not molded with precision, such that the molded case’s roundness does NOT closely match the roundness of the sensor mounting hole. As a result, the sensor quickly wedges and seizes up when only partially pressed down into the mounting hole. That is, my sensor at least, couldn’t be pushed down (i.e., fully seated) to the bottom of the mounting hole. I used the hammer and long screwdriver again to attempt to hammer it down into the hole. I got it almost down to the bottom of the mounting hole, but not enough to fully clear the snap ring groove so that I could not install the snap ring. I felt that it was tight enough that it wouldn’t fall out without the snap ring, so I just connected the sensor connector and tried running the car a few days in hopes that the AC would eventually start working. It didn’t.

I decided to try to remove the sensor to be able to file or grind it’s round part to make it more easily fit fully seated into the sensor mounting hole. I was able to force it back out by using my hands and fingers to wedge a small screw driver underneath the sensor and then pry it back out. One problem is that it caused a partial crack between the rounded part of the sensor and the protruding connector portion of the sensor. My crack was small enough where I decided that it was not necessary to purchase another $40 sensor. I would not recommend any attempts to manually force the sensor down into the mounting hole, or to manually pry it out, as there is substantial risk that the sensor will crack and may render it unuseable.

Once I got the sensor back out, I then found a rachet socket having a roundness which fit exactly into the sensor mounting hole’s roundness. That way, I knew the size of the sensor mounting hole. Then when I held the rachet socket against the round portion of the sensor, I could easily see where the sensor’s round portion needed some filing or grinding to make it more round. I used a grinder and got the round portion pretty close to the same roundness of the rachet socket. Once it was better rounded, the replacement sensor easily slid and fully seated into the sensor mounting hole. The snap ring groove was fully accessible again, and I was able to use my hands, fingers, and the “L-shaped” pick tool to install the snap ring.

Once I did all of the above (and reconnected the sensor connector and the alternator connector) and started my Sienna, my AC immediately started working again, and has been working for several weeks now. The fact that my AC would not work when the sensor was not fully seated down into the mounting hole makes me believe that the white oxide buildup might be the cause of the old sensor fail, and that it is important to substantially clean most of the oxide out of the hole and to grind or file the sensor body to make it better fit and seat fully into the mounting hole.

Hope this helps someone, gets their AC working again, and saves some money and landfill space.

afpj

Paultergei, Can you post pics? If you have to just do it again so we can see pics...just kidding! Thanks for the detailed write up. I’m curious if the oxidization crud is more from the salt belt areas.

Paultergei

Thanks for the likes. I don't have pics, but if someone needs a specific pic (e.g., the steel wool setup, or where to look downward in the Sienna to see the flow sensor), I can try to take pics. Didn't take pictures because I had tried many approaches for many weeks to try to fix this AC, and wasn't sure at the time if any one of the approaches would work. I can say that once I cleaned out the white oxide and fully seated the sensor, the AC re-start was pretty instantaneous, i.e., worked immediately without any delay. Re salt belt comment, my Sienna was operated mainly in the Washington, D.C. area, and salt is applied to roads here. I'm not sure if the white junk was oxide or salt, or maybe a combination of both. All I know is that it takes a little bit of pressure and scraping to get it off, and it comes off as white dust. As an afterthought, I often put Vaseline on my battery terminals to prevent them from oxidizing. I later wondered whether I should have put some Vaseline under my flow sensor to prevent oxide from forming there. If ever my AC stops working again, I will try to pull out the flow sensor again and look under it to see if oxide has formed again. If yes, I will clean out the oxide, and try the Vaseline trick. I'm not a chemist, but I don't think that Vaseline will interact negatively with either the resin body of the flow sensor or the aluminum body of the AC compressor. But maybe the heat of the engine would be too great so as to liquefy the Vaseline and have it drip out anyways. Over time, I would be curious to hear if anyone was able to successfully replace their flow sensor using the approaches I described, and how long it took (e.g., a couple of hours).

gettoki

Thanks tn7con my 2010 RX AC is fixed now. I got shop replace flow sensor from eBay. Finally cold air. They charged me $360 to install new flow sensor as booster circuit was not an option for me. They cleaned the area where sensor sits as earlier it didn't work. Hopefully this eBay part lasts for sometime. No more low voltage issue. Thanks all for sharing such a useful info.

tn7con

I'm glad it worked out for you finally, $360 is a lot better than $2000 for complete AC compressor replacement ...

sws299

Hi everyone, I stumbled upon this thread after searching thru the web for A/C solution for my Toyota Vellfire which I believe has the same engine as the 10rx - 2GR-FE.

So here is my problem,

The A/C on this car seems to be very sensitive to adjustment, for example if I changed the temperature to say 25-28 C, when I switch it back to say 20C, the a/c will no longer blow cold air, but instead only blow warm air out of the vent.

This has happened a few times in the following scenario:-

1. Front a/c blows cold air, rear a/c blow hot air even after setting the rear temperature to the lowest.
2. Front driver side blows cold air, front passenger side blows warm air.
3. Front driver side blows cold air, front passenger side does not blow any air.

Every time the above was able to be fixed by a dealer using the techstream tools with a couple of clicks in the A/C section and charged a couple of hundred bucks for a few minute work. Have gotten it fixed for about 4 times to date and the dealer has actually told me to change the damper servo sub-assembly (part id: 87103-58060) to fix this problem permanently.

I was thinking to learn & do abit of DIY myself and ‘reset’ the a/c myself. I have ordered the mini VCI port, downloaded the techstream software and learned a bit on how to use techstream on youtube.

Does anyone has any idea what might the dealer have done using techstream to fix the problem? (i.e. resetting the a/c?). Your kind advice & help is very much appreciated!

wkcr89tec9

Hello all, my internet searches brought me here and I am almost positive that this is the same issue for me.
I have a 2012 Scion IQ (I realize this is a Lexus forum) and my biggest obstacle is trying to figure out which wires are which.
Included is the wiring diagram for a Scion IQ 2012. I am not reading it very well but I think FLOQ is the flow sensor wire I have to tap into.
The second obstacle I am facing is the actual "booster" and putting that together. I have no background in electrical.
I have two pictures and a PDF attachment uploaded.

EDIT: The PINS are FLOQ for flow sensor, SG-1 for sensor ground and S5-3 for 5v reference.

OjeG

Mine is a 2013 Camry, shares same AC sensor.
Placing a little piece of neodymium magnet on the sensor (held in place by the snap ring) was all I did to get my AC working again.

The AC sensor definitely has some magnetic properties in it. My understanding of the problem is that the magnetism wears out due to heat, which in turn affects the required voltage.
Easy fix; my AC works ever after

Magnet on the sensor. Polarity matters

RX in NC

Well done....

Non

Thank you for sharing your fix, and for posting the picture.