Hello All,

I'm really confused about the temperature adjustment. I can have my temp set to 78 and STILL feel cool air coming out of the vents. I have to turn it ALL the way up to HI in order to feel the heat. I feel that, regardless of the outside temperature, if I set the car to 75 degrees, it should adjust to JUST THAT.... I notice this more when the weather is in the mid to high 60's. Any ideas?

 

You need to use a thermometer to see what the temp is coming out of the vents.

 

It takes time for the heater core to build heat.

Maybe you should come to Canada in January and take a drive. You can set your heat to "HI" and drive for 10 minutes and you'd still be getting cold air coming out of the vents.

You'll be thankful for heated steering and heated seats.

 

The air temperature coming out of the supply vents will always be MUCH lower than what the A/C system is called upon to match the thermostat. A temperature probe inserted into one of the car's front supply vents should deliver around 40° to 45° air temperature. If you open a supply vent directed on you, you can expect it to feel cold...and the cooler the ambient temperature happens to be the colder it will feel to your skin.

 

The temp outside yesterday was about 60, and I grabbed a thermometer from inside. After 5 minutes, the temp coming out the vents was 42. Today, the temp outside was about 50, and after 15 minutes the temp coming out the vents was 44. It seems the COLDER it is outside, the more accurate the temp is inside the car, versus what I've set it at. I don't think I should have to ride 45 minutes in the car, with a desire of 74 degrees in the car, but have my heat set on 85 degrees. If I SET it to 74, I want it to do what it needs to do to arrive at 74, and then automatically keep the temp there.

 

Have you even researched to learn how the A/C system works in your car? Are you using the Automatic mode? The upper supply vents may have colder output than the lower vents, especially when calling for a rise of cabin temperature on a sunny day. Keep in mind during reasonably mild temperature days it is actually more difficult to make occupants comfortable when the sun is shining in through the front windshield on the upper body while the lower body does not have that same occurrence. Your car's air conditioning system has sensors and a very intelligent and advanced logic system when using the 'automatic' mode. I doubt any other vehicle's air conditioning system is any better than the air conditioning system of the Lexus GS 350.

My bet is that your air conditioning system is working perfectly, but you can always have your Lexus dealership check it out for you.

 

I had some older cars cars that had the symptoms you describe. It could be a bad relay or a sluggish/sticky servo. I had a BMW that sometimes had to be rebooted (disconnect the battery) in order for the HVAC to regain it's sanity. I'm not saying your car has any of those issues, but there's a decent chance that if something is wrong, it will throw up a fault code on the dealer's diagnostic computer. The other thing you could do is find another GS 350 (dealer / private party test drive) and see if it behaves any differently.

 

One thing I have noticed with Toyota/Lexus climate control is the A/C compressor always comes on when Auto is pushed (except when the outside temp is very cold to keep from damaging the system). I guess they want it to run even in cooler temps to draw out humidity. It certainly comes on when you defrost, but maybe check to see what happens after you press Auto and then go into the climate control menu to turn off the compressor "A/C". That may help the issue.

 

That's EXACTLY what's happening. I'm saying, "It's 50 degrees out here now at 5am, and WHY IS THIS A/C running??????? If I turn it to "HI", I immediately feel the hot air coming out of the vents... Ahhh, it feels so good. BUT... I'm not happy that needs to be done. If the INSIDE of the car is 50 degrees when I get in, and I have 74 on the temp dial, the expectation (like what happens in my Caddy STS-V), I expect it to AUTOMATICALLY turn on "HI" until the cabin reaches 74, then I should hear the fan slow down and the temp become regulated... JUST like it does if I do it manually. If I MANUALLY adjust the dial up to "HI", the fan will begin to blow at pretty much a maximum. When I get warm, I DON'T adjust the FAN... JUST the temp down... and the fan AUTOMATICALLY slows down. I feel it should have done that with me having set the temp at 74.

If all my other cars operate this way, I'm not sure why the expectation would be different with the GS350.... I'm just confused.. and I appreciate all of you helping me. Maybe it's because my other rides are GM rides, maybe? 2012 Surburban, 2009 STS-V, and even the Dodge Charger (Hellcat). It's only my GS350 that operates differently. And I LOVE this car. (Although thinking bout trading up to a 460 F-Sport AWD or RWD).

Thanks all again. Guess I'm on the way to the dealer. I wonder if the temp sensor is damaged or something. It was just at the dealer because some wood flew off the back of a flatbed and hit it in the front (cracked the right-front headlight and fog lamp below it). Could it have messed up some sensor or something? Not sure where that stuff is located.

And yes, I've normally kept the AUTO settings in place, and just move the temp dial to the desired temp.