The thread gnonyx posted here:
http://www.ihadav8.com/forum/index.php?topic=3983 (I will cross post most of this on TBS.com) got me thinking about this conversion, I decided to try it on the 87T. I had rebuilt the A/C 4-5 years ago, but it stopped blowing cold, I still had R12 in the system.
It hadn't worked in ~3 years, but still had a bit of pressure. That's a good sign.
I purchased:
ACDelco 15-50120 Orifice Assembly
ACDelco 15-1681 Accumulator Dryer (This is the correct TR part #, despite what Amazon and RockAuto say)
Four Seasons 26777 Cap & Valve Air Conditioning System Seal Kit
This includes new valve cores for the system, and some spare caps. After much Googling and reading, a large amount of A/C leaks are from these. From the looks of the old ones, they may have been factory. All were replaced.
New Orings (I already have a shit ton of them)
8oz PAG150 oil
1/2 gallon A/C flush
4 cans 10oz office duster, Big Lots, $4 ea (only used 3) (They had R134 there for $6.75/can - with R134 being phased out, I am considering a bit of a stockpile)
New compressor seals - Got the wrong ones, another error from Amazon and Rock. Turned out to be simple orings I already had.
I went all out I guess. I pulled the evaporator out (That's another issue I read about - old evaps that get corroded/clogged, etc, especially pre-cabin air filter cars) and soaked it in a bath of home A/C coil cleaner. I gently brushed it, and cleaned it, used plenty of water. It didn't look TOO bad to begin with, but I swear I can feel more air volume in the cabin.
I did snap the evap cover when I was trying to remove it, this is the first time I have taken one apart. instead of Googling how to remove it, I went all cowboy on it. nothing a little silicone won't fix, and hey - it's gonna be my son's car soon. :p
I was not impressed with the amount of debris behind the wide trim strip and other parts I removed - spent a little while cleaning that up. I scavenged and reformed the black sealing goo and reinstalled it. I think I only stripped two screws - that's a win for me.
I pulled everything out, flushed it all (Except compressor) I pulled the compressor out and drained what oil out of it I could. I put a bit of the new oil in and rotated it a few times (Thanks Charlie!). I think this is the factory compressor, and has never been out of the car. I'm not sure. Either way, it's working. I ended up getting flush all over the left side of the engine - gave me a reason to clean up the motor a bit.
I installed all new orings, new orifice tube (old one pictured below), new accumulator and all new valve cores. Reinstalled it all, then realized I had forgotten to add oil. It was really late, I was beat - but I had to get the system buttoned up so I could put it on vacuum. As fast as I could, I put 2oz in the condenser, and the remaining ~4-5oz in the accumulator.
I put it on a vacuum for ~2 hours while I cleaned up, etc. I then left it for the night.
The next morning, I went and checked, no leaks. For giggles I turned the vacuum pump back on, it may have run for ~2 more hours.
I had a hard time figuring out the correct charge for this freon, I couldn't find a reference to that anywhere.
So, here's what I came up with, am I right?
Factory Charge: 3.25 lbs R12
HC152A molecular weight - 120g/mol
R12 molecular weight - 68g/molCorrected - thanks gnonyx!
HC152A molecular weight - 68g/mol
R12 molecular weight - 120g/mol
68/120 = .56
3.25lb * 16oz - 52oz factory R12 fill, or 29.12oz of HC152A/R152 (52oz * .56)
I was using 10oz cans, so - three cans should be a fill? Assuming ~1-2oz loss overall while adding freon.
When I took it for a ride yesterday with ~22.5oz - the center outlet temp got down to 51f. Ambient was ~80f, humidity was ~60%.
Idle, it will get down to ~55f. After reviewing my math above a bit more, I added ~5 more oz this morning.
Also - before I added anything this morning, the resting PSI is 85.5, and yesterday, I couldn't nook up my high side port, an oring popped loose in the connector. Then I realized this morning I could just remove the R134 fitting, and use my R12 high side hose.
Here's better the running pressures from this morning, AFTER adding a total of ~26.5oz (Estimate)
Low side - 37PSI
High Side 190PSI
Center outlet temp was 54, this is at idle.
I await the lambasting for something incredibly simple that I fucked up.
Some interesting links:
http://www.rx7club.com/1st-gen-archive-71/c-charging-easy-cheap-safe-alternative-refrigerant-997918/page4/http://www.s10forum.com/forum/f135/how-to-r152a-conversion-493953/http://www.sae.org/events/aars/presentations/2008/manhoekim.pdfPics!
Old orifice tube. Doesn't look too bad to me - experts?
Suckin!
The bad part is I found out the driver's side upper control arm bushings are completely shot - it explains the random clunking. I think I will wait for the son to come home on leave - he needs to learn how to rebuild a TR front end. :p
Kinda hard to see in this pic, but they are the worst I have seen. Oddly, the passenger side bushings look tired, but they aren't disintegrated like the driver's side.
