This is driving me crazy so I thought I would see if anyone else has had this problem.. 2008 rx 350.. Recently I noticed that when I run the heat its not as hot as it use to be. Fan is working great.... The heat works awesome on high heat but every other temperture it feels the same, i.e. not very warm. As a shot in the dark I replaced the thermostat but that did not solve the issue. Car is not overheating or loosing any fluids. Other than this issue it runs like a champ.. Any thoughts?

 

Usually just to the left of the stereo towards the bottom, near the key location, you'll see a small inch size square with several slit holes in it. That's the cabin temperature sensor back there, over time it can get clogged with dust. Get a tv dial cleaner, aerosol can, and blow air into holes. the sensor may simply be dusty.

Also check and replace as necessary the cabin air filter if you have not done so, this will affect HVAC in the vehicle. I just replaced mine, I could not believe what I saw, pretty nasty. I am having a bit of a problem with the A/C and replacing the filter made it a bit better.

 

^^^ Good to know. Thanks for the info.

 

So I went over to a my best friends house who also happens to be a VERY genius kinda mechanic. I had dinner then relayed your question to him as mine felt the same. Well he comes back in with a digital laser temp gauge and said let's go take a drive. After setting the temp to 80 after proper warm up the gauge showed 82°. On HI it registered 115°
Radiato showed 175°. Ha! We had fun taking temps of various car parts. Gas stove 1125°…
So whe it may not feel like 80 it is. Buy a digital temp and you should be good to go.