450H Cooling Issues

[az-tinbender]

Greetings Members,

I just joined the group in an effort to reach out and see if others are experiencing similar issues that we have had with our cooling system.....

Being an owner of both Scion and Toyota vehicles we were excited about purchasing the 450H in December 2011, now we find ourselves so disappointed with our experience we believe both quality and service are oversold, to that avail we may never purchase another Toyota product....

Let me start by saying being an Arizona resident likely challenges to a exceptional cooling system, however we have had ongoing cooling issues after leaving the 450H sitting in the sun, after several occurrences I places a thermometer in the vents to monitor the cooling temperature and noticed the vent temperature only drops to 50 degrees after sitting in the sun, after driving for 30+ minuets the temperature will drop to 36/38 degrees and properly cool the vehicle, unfortunately your leaking sweat all over those beautiful leather seats in the mean time.....

We have had this into the dealer multiple times, they did duplicate the issue once however have not been able to reproduce since therefore have not fixed anything.....our service writer at the time asked what direction we were driving when this occurred, my response (are you kidding me, it should cool driving any direction, what happens in a round-about).....anyway, the dealer recommended we call the Lexus line 1-800-255-3987, the squeaky wheel gets the grease they said....after doing this Lexus reviewed the service history and said "there is nothing we can do if we can't find the problem"......this is the Lexus model? wow......I could have purchased a much cheaper vehicle with a broken air conditioner....

Perhaps someone in the forum has experienced similar issues that could help lead us to resolution.......

Cheers,

[Buk]

I never realized it would output 36/38 degree air. Seems really cold. You made me want to check mine out.

What is your outdoor air / recirculation air doing during these transitional periods?

Just as an incidental question, what color is your interior?

[az-tinbender]

Hello,

Actually the dealer agreed that normal vent temp would be in the 38 degree range.....my Toyota truck delivers 34 degrees at the vent....one might think that 50 degrees would be sufficient however we need to be mindful of the cubic volume involved.....as described this condition is without outside air circulation, considering our ambient temps it would be impossible to cool by injecting outside air.....the interior is light tan (does have a black dash).....exterior is light as well....agreeably color does have an impact however if the vehicle doesn’t cool properly in black or other dark colors those options should not be available....

Thanks for your input....

[lenore]

Weird, our old RX300 and our present RX400h both cool incredibly well...our tempertures have only hit 105 degrees here. The RX450h uses an electric compressor, but it should still be very efficient. Your temps are good coming out of the register...

[Buk]

Your dealer may have asked about direction as the car has a sunlight sensor. The sunlight sensor, ambient temperature and cabin temperature all play a role in how the A/C functions. In addition to possibly a smog sensor. Plus how you have all the controls set, which I'm going to assume everything is in auto and temperature set as low as it will go(?). Just remember the car remembers the settings associated with the key fobs. So if the car is locked and you use key fob A to unlock the car, the settings will revert to those settings memorized and associated with key fob A. If key fob B has a different set of settings memorized, those setting will be called up when key fob B is used to unlock the car. Of course, if you just get in the car and adjust everything, the settings memorized have no bearing.

As Lenore has indicated, the compressor [usually] is efficient. It's a variable speed electric compressor.

If the car is under warranty, continue in your efforts for a solution. Until then, I might suggest continuing to monitor the fresh air and recirculation air LED's for any anomalies you can report to Lexus. Guessing from your username, you are familiar with all of this discussion. Fan speed will also play some role in outlet temperature (depending on compressor output), but a slower speed will have a colder temperature as the difference in temperature across the coil will be greater. As you mentioned volume, a higher speed with help with the volume of air involved.

Now I gotta find a thermometer and check mine.

[az-tinbender]

Greeting Buk,

Your feedback does bring additional food for thought to the discussion, I had not really considered the key fobs being a factor, I don’t this is associated as the AC seems to self correct during extended drives nonetheless a different angle to consider and factor…..I guess all I know for sure is something, control, sensor or other is making improper cooling decisions…...the second time we took this in we actually received the same exact vehicle as a loner which seemed to cool the vehicle effortlessly…...the loaner showed 38 degree vent temperatures…..

Thanks for your feedback

[Buk]

AZ -

A couple of thoughts, first there may be nothing wrong (although you seem to indicate your other cars don't react this way). It may take a while for a car with a black dash sitting in the sun and 100+ outdoor air temp to start cooling down. If the fresh air/recirculation damper is working, fresh air should be shut off and as recirculation occurs the discharge air temp will slowly drop.

Whether the car is stationary or moving, may not matter. Have you tried just starting the car and sitting still and monitoring discharge air temp. It could be dropping in a manner similar to when you are moving. Therefore motion has no bearing on what you are experiencing.

While it is entirely possible one or more of the input sensors is defective and the computer is making bad decisions based on those sensors or it could be defective making bad decisions on it's own and or the output servos are not working properly.

Not sure what model year your RX is, these switches vary by model year, but try messing with the fresh air / recirculation air switches see if they really perform any functions. Listening and or monitoring discharge temperature may give you a clue.

I think a service tech can take some resistance reading of the input sensors to determine proper functionality and probably check their function when they plug in their service laptop. The ambient sensor and the smog sensor are in the engine compartment or in front of it, the sunlight sensor is on the dash and the cabin temperature sensor is an aspirating sensor located behind that little vent to the right of the steering column.

Lastly, you can just keep dragging the car to the dealership and keep beating on them for service without doing all this self-testing. It's under warranty!!!

Best of luck,

[Sgull]

We have a 450H and live in Clovis, (aka Fresno, CA) so we have the same daytime heat as you do in AZ.

Ours is a dark exterior and the black/buckskin interior.

We have not had any issues getting our interior cooled down within a reasonable amount of time, even being parked for hours in 105 plus dgrees.

I do notice that the heat coming off that black dash is incredible.

My wife uses a sunshade most of the time, helps a lot.

Now you have me curious, let me pull out my thermometer and see what mine does!