Air Conditioning Died - 2010 RX35k0

[Tatoosh]

The day we bought our used 2010 RX350, the a/c died.  A trip to a reputable repair shop told us the problem was in the compressor and that it would be $2100 to replace.  We were dismayed at that to be sure.  But the wife loved the car, it looked in pretty good shape otherwise and we kept it.  I started looking around and in a different forum, found a thread on a/c problems, not just for Lexus but for other Toyota's as well.  And based on the fault showing in the Lexus Diagnostic Software (and probably from an OBDII scan), it may simply be a bad sensor, which Toyota recommends replacing the whole compressor anyway.  But there are a couple of cheaper potential solutions.  

Three different approaches worked for some, but not all the folks experiencing this problem.  The problem, it seems, is that some sort of powder builds up around the air flow sensor, causing a weak signal.  Once the signal drops below what the on-board computer needs, it never reads the required signal and the compressor simply doesn't work, but it could.  So the first guy fixed it by creating a small in-line amplifier that brought the weak signal up to minimum strength and he got his a/c back.  The second guy, more of a back yard wrench, pulled the compressor, removed the faulty sensor where he found the offending powder.  After one false start, he got his a/c back by very thoroughly cleaning out the sensor mounting hole, getting a new sensor, sanding its exterior so it fit the mounting hole perfectly, then installing so it was snug and fully inserted into the mount.  His a/c came back.  Two solutions.  But there is a third one, even simpler, that might work.  This one was found by a Camry owner, which used the same compressor.  

The third guy took a one centimeter square neodymium magnet and placed it directly on the sensor, being sure it also stuck to the metal retaining ring (sort of a C-Ring).  The build up of the powder noticed in the second solution apparently diminishes the magnetic field around the air flow sensor.  The addition of a strong rare-earth magnet amps up the magnet field and as long as the polarity of magnet is correct, the air flow sensor's signal is back within tolerance for the on-board computer.  Can this really work?  Well, yes, it can.  

I tried it on our RX350 a few days ago.  The air conditioner had been blowing hot air regardless of what we tried.  The mechanic's dire prophecy meant we were resigned to dropping a couple grand on fixing it.  But $5 worth of magnets from Home Depot fixed the problem and it's been working for over a week, with the car driven daily, including a nice 20 to 25 mile jaunt on the interstate.  I got a package of 3 small 1 centimeter circular magnets.  These had holes in the center.  The original fix used a square, solid 1 centimeter magnet, so I doubled up and used 2 of the magnets from a package of 3.  If your a/c is dead, it may be worth a try.  Good luck!  

The code showing in the Lexus diagnostic software is: DTC B1479