Plug Guy

2007 RX400h
Working fine otherwise, no major issues

Noticed a few weeks back, about 39 degrees outside, temp set at 72 auto, and warm air from vents, about 10 minutes into driving the air went noticeably cooler. There was no big temp change outside, still 40 or just under, and cabin was fine, but not toasty warm.

Figuring either an inside temp sensor is going bad, or something amiss with the HVAC, which works fine otherwise.

I searched the boards and looked at coolant levels, fine and at the right mark. This happens just about every day.

Any other thoughts?

nmmuzykam

My 2007 RX400h does the same thing, I think it is part of the system design, and it is normally noticeably cooler because the system switches from the floor vents to the upper vents, which are only used to release cooler air (according to the presets by the Auto system). If you turn the heat up to a different temp, it should switch back to the floor, and release hotter air again. I usually have it set to 74 or 76 so that it doesn't occur as often. However, I have found that when it switches to cooler air, it actually makes me more comfortable as I have started to get pretty warm by that point. Hope this helps!

Plug Guy

OK, but this JUST started a month ago. Had the car since new, never did this before. It can't be normal.

nmmuzykam

Have you always had it set to Auto? Either way, if it really bothers you, I would ask a dealer.

Plug Guy

Mostly auto, but manual too. Trying to avoid dealer visit.

redrocks

"Trying to avoid dealer visit." Dealer too far away or bad experience with dealer?

Plug Guy

Oh no, our local dealer is stellar. Out of warranty, not a major issue, might wait for something else or see if it gets worse.

vg1134

sounds like the inside temp sensor is faulty. no way to tell unless you do a diagnostic.

redrocks

Well, maybe they'll cover it (good faith). No vehicle should be having HvAC issues with only four years of age, especially a Lexus.

Rainbird

I have the same cold air problem on my 2007 RX350. Being that I live on the Central California Coast where the temps are somewhat mild it is not a big deal. In the Winter I set the temp at about 76 degrees and even then it will start blowing cooler air after a few miles. Now, if I lived in snow country I would be really upset. The vehicle is now out of warranty, so it will stay the way it is. In some ways I miss the old slider temp and select fan speed controls!

redrocks

There's always manual mode, you know.

Rainbird

I don't use "Auto" mode I set the temp manually.