Many thanks to Shifty for pointing me in this direction.
Here's a quick guide for converting your AC system from a GM R4 compressor to a Sanden style unit. I did this on my 89 Suburban with the 6-groove serpentine belt setup.
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Every year, the death struggle commences in March when I begin trying to resurrect the ACs in my ancient cars. Every year I spend a bundle on parts, and throw away entire weekends on dismal failure. Every year, by September, I give up in disgust. I don't know why it's so hard to keep old ACs running, but it's been impossible for me so far.
This year has been typical. I bought not one, but two R4 compressors from different manufacturers that were junk right out of the box.
https://1drv.ms/v/s!AmykSvd_9WdWhOMKCkqif6BxDmqUbw?e=lx5BFG (Link to my OneDrive account)
It costs a weekend and $120 worth of unrecoverable materials to charge a system and fail. Enough of this parts store nonsense. I'm going aftermarket.
Here is my new AC strategy, based on five decades driving very old cars in an extremely hot climate.
- Run your AC until there's a problem that requires you to discharge the system
- At that point, replace everything, stem to stern
- Use only new parts from reputable suppliers
- Where possible, swap components to aftermarket equivalents. In general, aftermarket parts are better than what you'll get from O'Reilly or Autozone
Think of it like your home AC. There comes a time when it all needs to be replaced with the latest and greatest.
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You will need the following items for the conversion.
I would also recommend you read through Sanden's excellent materials.
There is a lot of great info out there on flushing, vacuuming and charging your car AC. In the interest of brevity, I won't go into any of that.
After removing all your old AC parts, begin by installing the hardest-to-reach parts first, like the evaporator and condenser. Put a white orifice tube in the evaporator (make sure you point it the right direction, not like I did).
Then install the compressor with the adapter bracket. The bracket comes with a lot of spacers of varying sizes. Here's how you want them to look when you're done.
Or perhaps a better pic from Dirty Dingo's site.
Make the lines next. I got the line kit from Vintage Air that seemed best, but there might be something better. You need to make 2 lines. One is a #8 with 2 right-angle fittings. The other is a #10 with 1 right-angle fitting and a ~15° fitting. I just played around with fitment and length until it looked right, then crimped the new lines together. Here's how it turned out.
You'll notice the pink marker on the lines denoting the correct orientation. Make sure you get the orientation right. You don't want to twist your lines because you crimped a right-angle fitting pointing the wrong direction. The Vintage Air kit has a variety of crimp fittings. Some have service ports on them for your gauge set. I wanted to preserve my factory service ports and intended not to use any of the service port fittings. I was forced to, however, because the kit I chose didn't have enough bare fittings. It ended up working in my favor because the extra port helped me diagnose a bad [old] condenser (that I am now replacing). Again, you aren't going to save any money by trying to re-use your old parts, even if you are sure they're good. After 10 years, they probably aren't. Just replace everything.
The crimper tool was a classic example of what I call the "Chinese tool problem." It came leaking oil in the box, and leaked oil for the entire job. We tried to fix it, but it was no use. It was a fiddly nuisance, but it was cheap and
finished the job well enough. You hate the tool, but you keep it around because it does work in the end.
Next install the accumulator. Vintage Air sells their own kind of accumulator. I wanted to use a factory accumulator, but the unusual thread size requires you to adapter down to accomodate your custom hose fittings.
It's possible Vintage Air sells a line kit that includes the giant accumulator fittings on GMs, but mine didn't. If you find a better line kit, definitely post below.
I wanted a Deutsch connector for the clutch wire to make for a more professional install.
I like Deutsch connectors because they are clean, easy to use and don't have sharp edges like many other connectors. The Sanden compressor comes with a single wire. The factory clutch uses 2 wires, green and black. The green wire is power. The black wire is ground. Connect the green wire to the single wire on the compressor. Then run a length of wire to ground on the compressor body. Like so:
The factory serpentine belt is 96" long. The new compressor adds 2" to that length, meaning you need a 98" 6-groove serpentine belt to preserve your factory belt routing. I believe the Gates 980J6 will work, but I haven't tested it. My current belt cost $80, is brand new, and I wanted to run it longer. I bypassed the idler pulley and it works great.
If you need a diagram, just follow the "without AC" path on the sticker on your fan shroud.
Note that routing your belt this way does not alter belt tension, but does decrease belt contact on your compressor and crank pulleys.
Finally, unseal your accumulator, put your adapter on and install it. You're now ready to put oil in your system.
Regarding oil, Sanden's part numbers can be confusing because they make each compressor in both an R12 and R134 version. Same compressor, but different part numbers. The 134 version of my compressor is an SD5H14, but the R12 version is a 508. Be aware of this, because in most cases, you don't want the compressor filled with R12 oil (the 508).
The compressor comes pre-filled with the right amount of oil: 3 oz. It's filled with Sanden's proprietary SP-15 oil, which I believe is equivalent to PAG 150. You want 8 total ounces in the system. Add 2 oz each to the evaporator and accumulator. Add 1 oz to the condenser and you're done. Note that Sanden's oil is hygroscopic (it absorbs moisture). You don't want to leave the bottle (or your system) open for any longer than you must.
If you opt to keep some old parts of your system (you'll be sorry), Sanden wants you to flush them very thoroughly "until clean flush comes out." They also encourage you to back-flush, or run your flush in the direction opposite of the flow of freon. Dry as completely as possible, then run your vacuum pump for 45 minutes to eliminate all traces of flush.
A word about condensers. The factory condenser is a linear flow design. It works great, always has, but the cool kids are running parallel flow condensers now. Parallel-flow condensers are more efficient, but they can't be flushed. If they get trash in them, you have to replace them.
You're ready to vacuum and charge! I like to pump down my system and leave it overnight to make sure there are no slow leaks. Before you enjoy the wonderful cool, however, you'll want to address one final wrinkle. Because the Sanden compressor is longer than the R4, it hits the air cleaner body. You can sort of force it all together and make it work. The air cleaner sits a little cockeyed, though, and will probably carve a groove in your expensive, custom hose fittings. I asked my nephew, who is far better at welding than I am, to clearance it for me.
Lovely work:
Makes the rest of the bay look even trashier, doesn't it? I also lost the spring for the heat riser valve. Doh.
Anyway, that's it. Enjoy the cool!
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