heshamos

It seems that the sensor gets a signal from ECU to activate/deactivate a magnetic field to utilize the compressor. Placing a strong magnet there might close the circuit to run the compressor but it won't disconnect it. Makes sense? Trying to figure out what's wrong with the issue.

wwwjogos, How much is the new sensor? Where from?

Cheers

OjeG

Mine cycles;....... Actually it's been almost a year (and about 15,000 miles) since that experiment; AC still cools. The sensor I bought from AliExpress is still unused.

alpinefun

Thanks! I see your point. I will try to use a smaller magnet - will see what happen.

alpinefun

Thanks OjeG. I am using the 1/2" dia x 1/8" thick cylindrical magnet. I will replace it with rectangular one which is not as strong and will see what happen.

wjz

Our 2011 rx350 ac stop to working two weeks ago. AC flow sensor voltage was 3.66V.
Thanks OjeG, y7wu and tn7Con sharing their experiences with ac flow sensor. I brought a magnet bar from amazon and broken it to 10x13x3mm then put on ac flow sensor. Wow, AC start working. AC flow sensor voltage increased to 4.31v when AC off, 3.8-4.31v when AC on.
I changed the magnet size to a smaller size, app.10x4x3 mm, AC is still working. The voltage reduced to 4.01v when AC off, and 2.5-3.22.v. when AC on, which is in the range of the flow sensor normal ranges.
I also brought an AC sensor from ebay, but not used.
Thank you OjeG.

alpinefun

WJZ, Please confirm that your compressor cycles when AC system in Auto mode. What the interval time between cycles?
Thank you.

wjz

alpinefun, I am not sure how to check the compressor cycles. in hot days, I guess ac compressor will be on all the time.

alpinefun

WJZ,
I believe by design the compressor shell be some time (for about 30-60 sec?) on and then when the pressure gets build up the pressure switch should turn it off (for about 30-60 sec?). Guys, please correct me if I am wrong.
The easiest way to check it is to let the engine run, turn AC On, open the hood and watch if the compressor clutch gets engaged (compressor On) and disengaged (compressor Off). You will see and hear it.
You can also watch yuor tachometer with engine idling - revs will go slightly up when compressore gets on.
I have installed the magnet and that fixed the problem. However the compressor is always On. Trying to figure out if it is normal.
Thank you.

wjz

apinefun,
I started car, push auto/ac on, set temp. at 72 deg. the engine ran 6 min, the compressor was on all the time. I do noticed that the fan speed changed from high to low slowly,
When i turned ac off, the compressor stopped. I am not sure the ac compressor shall switch on/off every 60 sec. May be dealer can help?
thank you.

alpinefun

WJZ,
Thank you very much for checking your compressor. This is exactly what my car's AC system does. Maybe it's normal when engine idles. Not sure.
I wonder if other people can share their observations.

Nickyboy90

So I was I had this same problem for over two years on my Scion and today 5/25/20 was the day that the magnet trick did the trick. I want to thank all of you for this. After looking everywhere for two years and trying to find a fix with out spending $2000 even looking on a Scion form. I can say my ac is blowing a perfect 50.4F

afpj

Alpine fun,
I I suggest checking function either by using techstream to check the voltages as above, or setting the temperature to something like 80 rather than a low temperature and making sure your defrost function is off, and seeing if it cycles with a higher temperature setting.

johnusl52

I was able to fix the AC on my RAV4 by adding a small piece of magnet to the flow sensor following instruction provided previously by others.
I added the magnet by opening the engine hood and putting it on by hand. Took 15 minutes from start to finish.
Thank you so much, saved me $2000 to replace compressor and time. I think the magnet somehow amplify the electrical signal going into the sensor for it to read correctly.

gasal21

HELP- 2011 rx350 AC issue. After turning on vehicle AC wont turn on for about a minute, then green light turns on an so does AC.- Driver side blows outside temp air, Passenger side blows COLD air. After reading previous posts i bought a new AC flow sensor from Ebay and had it installed by a mechanic, i emphasized to mechanic importance of cleaning the space where the old sensor sat (he said they did so). New AC flow sensor install did not remedy my driver side warm/passenger cold issue. What should be my next step? Im close to biting the bullet and taking to a dealer as i start a new sales job next week and will be driving alot here in South Texas heat index was 110 yesterday! Thanks in advance! **PS this is a great group!, im not mechanically inclined and this is my first post!

RX in NC

Most vehicles with dual climate controls in the cabin have what is often referred to as a dual climate control valve (DCCV) as part of the cooling system. It could be that yours is stuck or clogged. It could also be because one or more of your HVAC blend doors in your dash vents are stuck because one or more of the servo motors that control them has failed. Sometimes cleaning the servo motor contacts can fix the issue as opposed to spending the money required to replace them.

If you opt to take it in for diagnostics, do not go to the dealership. Find a local indie automotive HVAC shop with a good reputation. They are far better at HVAC repairs at a much fairer price than any dealership will be.