Lexus Repair: LEXUS REPAIR, lexus factory, mechanic work

Question
I have 1993 ES-300 with 180,000 miles. It's burning a lot of gas, so my husband cleaned the throttle body, and change a O-Sensor might not be the corect name, but I know it was pertaining to gas. Now the white smoke comes out of back pipe, in which it never smoked before the repairs. My A/C also went out, I got that check my a mechanic, they say my compressor comes on. But the LExus dealer don't repair a/c they only replace the whole system. So if the compressor comes on what is problem, and why is car smoking and burning a lot of gas.  

Answer
Hello, The white smoke can be caused by valve guide seals. This is common on the ES Lexus and it is mostly a problem that happens when you first start it in the morning. I have never heard of the Lexus dealer not fixing a problem and replacing the whole system instead. I would say that it could be your a/c expansion valve. A quality mechanic should be able to fix shis. I would only let a quality Lexus factory trained mechanic work on it though.