semlin

hi, i just bought a 91 ls400 that has been parked for 3 years and has done 5000 miles in 7 years. it has 134k miles. It was converted to 134A more than 3 years ago but exact date unknown. The conversion sticker says that at conversion 29.5 ounces of 134a were added and 4.5 ounces of oil.

the ac light comes on and does not flash but it does not blow cold.

I pulled the AC trouble codes using the lexls.com tutorial instructions. I get code 33

"Open in air mix damper position sensor circuit. Or, open or short in air mix servomotor circuit. Or, air mix servomotor locked."

does anyone know what this means? i googled "air mix damper position sensor circuit" and it appears to include the regulator that shuts down the compressor if rpms exceed or go below set minimum/maxes. is this code going to appear automatically if you have low coolant or does it mean the compressor is bad?

I also had a mobile AC guy come by to recharge today. He found zero pressure in the system and declined to recharge. He wants me to take it in to the shop for a $150 diagnosis.

before I go I'd like to know whether the trouble code already tells me what my problem is. I'm also curious about the 4.5 ounces of oil. That sounds like about half what I'd expect and the AC guy agreed.