| When I first bought my Z a few years ago the AC worked great. It wasn't until I pulled the engine the first time that it began to blow warm air. I assumed that I must of damaged the evaporator or expansion valve while forcing my new efi harness through the firewall. Well that or allowing the ac compressor to hang from it's lines for a few months some how allowed the freon to escape. Before deciding to do a proper conversion I figured I would see if the r12 system could be cheaply repaired. I had the remaining R12 recovered which happened to be about .8 pounds. Next a vacuum was put on the system for 20 minutes and then held for another 20 minutes and found that the system seemed to have no leaks. Now I was optimistic that a proper refill would fix the issue. Nope, still warm air. I later found out that the issue was a stuck suction throttle valve that is NLA. Here's my tech post:
http://twinturbo.net/nissan/300zx/forums/technical/view/1103948/Need-advice-on-course-of-action-AC-related.html So I decided a full retrofit was in order. I began with a lot of researching here and found a lot of good info (most from member Aliaz). Here are some good links on AC systems and flushing techniques: flushing ac system
*Look for FLUSHING TECHNICAL PAPER vs2.pdf link flushing compressor It was recommended to me to use mineral spirits as a flushing agent. This worked excellent for the used evaporator I bought and all of the ac lines. I borrowed this technique from step 7 to force the mineral spirits through the lines. It worked wonderfully. In order to flush the evaporator you must remove the valves as they cannot be flushed through. This requires removing the AC box from under neath the dash. This can be done without removing the dash. Flush from high side to low side. For the compressor you should flush with new oil of whatever type you will be adding to your new system (ester oil in my case since I was converting). Here is a list of parts I replaced for my conversion: -I purchased a working evaporator/expansion valve/suction throttle valve from a forum member. -drier
*Good fit -o-ring kit
*This kit had suitable replacement o-rings for every o-ring in the system with the exception of the large o-ring within the suction throttle valve. I recommend buying this from nissan as I had to visit five different local stores to find one. None of the auto stores had anything close...ended up finding one at a local industrial hydraulics shop. -binary switch
*Good fit -two bottles of ester oil
*One bottle for flushing the compressor and one for filling up the system. This is plenty enough. -Z1 replacement condensor
*Good fit however I was not impressed with the fin density or number of passes compared to the oem condenser I removed. I believe this is considered a tube and fin design. I replaced my condenser since the fins were very clogged and blocking air flow to the radiator. For best results with 134a you should use the parallel flow type condenser found on the late model z's. -Conversion fittings that can be purchased at most auto stores. -I also bought a vacuum pump and gauge set so that I could do my own maintenance and troubleshooting. In the end I am very happy with the results. It blows very cold ( comparable to my wife's '09 Nissan Rogue). I believe the only thing that could have made it better was an oem parallel flow condenser. Flushing note:
If anyone believes that flushing is not necessary you are crazy. I flushed both my old and new evaporator and found a ton of residual freon and mineral oil in them. Same goes for the compressor. My r12 was professionally recovered before hand yet it is obvious that only so much can be vacuumed out. Fortunately for me I was replacing the condenser and drier so I did not have to flush those but I imagine those would have tons of residual oil and freon as well. This is mostly just compiled research but I want to thank member Aliaz as he has provided this forum with tons of great info regarding the ac system.
 Formerly: ZEVAN (Ca), Evan3zx(ca)
Xbox live GT: kidding Me
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