Just bought a 2nd gen GS300 but when I turn the temperature up, the drivers side still blows cold. Also the air is not blowing high either. Not sure if it's servo problem.

 

Sounds a lot like the servo.

 

Same thing happened to me and I thought it was the servos as well since I've been hearing the 'mouse scratching noise for some time. I bought the servos but never installed them. Turns out I was really low on coolant. Weird thing is the radiator always showed full. Eventually I parked the car facing up an incline and checked the radiator when the engine was cold. It was empty so I filled it along with the reservoir. Had to do this a few times until it filled completely.
Problem went away. I still need to replace the servos because the scratching noise is annoying.
This all happened about 2 years ago.

 

I send a few thread that you need to check. This is one of them;
https://www.clublexus.com/forums/gs-...iver-side.html

 

Another thread;
https://www.clublexus.com/forums/gs-...rt-number.html

 

Recently my gs430 also did only blow cold air, except on the highway temperature got up to normal. turned out to be the thermostat, had a broken rubber seal.