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Discussion Starter · #1 ·
I thought I'd share how I got my ac going in case my experience would benefit anyone.

I got my 85 with auto climate control around 2001 with ac not working. Over the years I pulled off all the ac parts, I guess because ac wasn't on my mind. But at a certain point I decided to start rebuilding it. It turned out to be beneficial to have everything removed anyways.

I decided to convert to R134A.

The evaporator for the auto climate control has a suction throttle valve. I had no idea how to recalibrate it for the R134A or whether it was clogged or not. I decided to use the simpler evaporator instead that has no STV (salvaged from another z31). It still accepts the superheat switch, and I tested the superheat switch/timer too. Also I cleaned the fins thoroughly.

I flushed the evaporator, condenser, pipes/hoses. Because of how the evaporator is designed, you can't flush it on the car. Even when you have removed the evaporator and the expansion valve, you have to get creative with your flushing setup.

I got a rebuilt compressor (300zxpartsforyou.com) but replaced the PAG100 oil with PAG46 w/ UV dye. New drier, a used dual pressure switch and safety valve from a 1994 300ZX, new idler pulley, R134a adapters for the service ports and new o-rings for every connection. I removed all the old crumbling insulation from the pipes, cleaned and checked for any damage and wrapped with new insulation. Never could source a new expansion valve, at least not a direct fit one. I just cleaned it as best as I could and replaced the large diameter o-rings on it.

Once I got everything installed I vacuumed the system and it held vacuum, then I charged with R134A.

The ac works well. I let the hot air out of the car first, then set the ac to the lowest set point and recirculate. I have no tint on my windows but I do have t-top shades. I live in central Texas, pretty hot here.

I attached a Nissan service bulletin that I used and of course the FSM was a big help.


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