I've been running a few threads w/ questions about converting my 1989 740 (2.3 SOHC) to R-134a and I thought I'd consolidate now that the system is in and hooked up.

I ran into a few problems that folks should check for carefully, since I cannot believe mine is the only one-

1) The Hot Air Hose from the exhaust manifold chaffed through the suction hard-line (down by the left front frame rail) and caused a refrigerant leak. This hose in NO LONGER AVAILABLE, and FCP said the only hose that would fit was a special order one for $138, but I found their #1348538 hose at $24.95 fits perfectly, though routes along the firewall.

I am attaching Picture 1 showing the routing of the "new" hose at the Accumulator (Copy and Paste): http://screencast.com/t/JP9cinz0

Note that after this picture was taken, it became obvious that there wasn't room for a large low pressure QD fitting to fit onto the Low Side Port on the Accumulator (Under BLUE cap shown w/ Red Arrow) as it was blocked by the ignition coil. I just re-drilled the coil mounting bracket holes an inch rearward and everything now fits perfectly.

2) I found a pin-hole leak in the hard-line from the condenser to the evaporator right where the flare nut was in contact w/ the aluminum tubing at the condenser fitting. The area was corroded somewhat from what appeared to be dissimilar metal corrosion. Volvo can still supply a replacement Part# 3522266 for about $100, but since it was a special order item (w/ delay) I TIG Welded extra aluminum onto the line and filed it to the original profile to remedy the problem at no cost.

I replaced the Accumulator w/ supposedly an R-134 one from FCP for $28, though it appeared identical to the OEM R-12 one, so needed a R-134a low pressure service port mounted over one of the Shrader valves ($6 at O'Reilys). I added a R-134 adjustable compressor switch I also got from O'Reilys, and a Variable Orifice Valve that supposedly improves low rpm/hot-weather performance ($19). I replaced the high pressure flex hose for preventative maintenance w/ FCP #3537728 ($38.95), and the Condenser for good measure with a Nissens unit from FCP for $80. My old condenser appeared to be fine, but after the other leaks I found, I just didn't want to fool w/ it for $80.

On the advice of a Brickboard member, I replaced the existing Diesel Kiki compressor with a Sanden 709 as it supposedly takes MUCH less hp to turn at low engine RPM, and supplies more volume for much better performance at the same time. These can be had new for about $120 or less from ebay. Mine was labeled "R-12" so I just drained the mineral oil and re-filled with Ester Oil for R-134a ($10 at O'Reilys"). The drain/fill port is the threaded plug shown at the RED arrow in the photo below, and the compressor took 4oz.

Also note that when using the Sanden in place of the Diesel Kiki, you must attach the rear compressor mounting plate in FRONT of the mounting ears rather in back as w/ the D-K compressor because the refrigerant fittings are so close to the ears. Just use a spacer to mount the plate to the car's rear brackets and all is well.

Also note the "V" canted ports on the Sanden vs. the parallel vertical ports on the D-K. The aluminum tubing for the hoses is plenty soft to be bent by hand pressure alone-no tools necessary.
Copy and Paste Picture: http://screencast.com/t/MbFVUnbn

I bought an "O-Ring" kit from O'Reily's, but only a few of the O-Rings were exact fit, so I let FCP send me the proper ones with their hoses to be sure. I used "Nylog Blue" at all "O-Ring" connection spots, though you could lube the O-Rings w/ Ester Oil.

I installed a small DIN relay and control it with a wire from the compressor clutch wire to supply power to the electric pusher fan anytime the compressor is running, which lowers pressures and helps cool better at slow road speeds.

I replaced the blower fan assembly with a genuine VDO unit for only $27.90 from O'Reilys, and it flows a LOT more air than my old one. Not sure if it's a design change, or just age.

I finally drew and held a vacuum tonight, and tomorrow I will fill the system w/ 31oz of R-134a (about 20% less refrigerant than R-12) and will let everyone know how the Sanden compressor and the Variable Orifice work.

Admittedly, my conversion cost of about $400 was NOT cheap, the ONLY component retained from the original system was the evaporator. If you live in hot country, and plan to keep your 700, $400 is not an unreasonable cost to have a good A/C system. If my car were not going to live in Phoenix, AZ maybe a quick-and-dirty conversion would have been fine, but I knew AZ temps would challenge the old components to the point of discomfort.

If you plan to finish the job yourself, and your system is already empty (so you don't need a refrigerant recovery system), you can buy a decent set of gauges from Harbor Freight for $58 and a Vacuum Pump from HF for about $110, or a better Robbin Air 5CFM pump on ebay or Amazon for about $160. R-134a refigerant is about $15 for 12oz at WalMart, or $7 from Tractor Supply (I don't know how TSC sells it so cheaply). You'll need 3 cans and a "Can-Tap" to hook the cans to your gauge system (Under $10). There are YouTube videos that are very explicit on evacuating the system and re-filling with refrigerant, so you don't need to have any prior knowledge to do a good job.
YouTube1: http://www.youtube.com/watch?v=F5w3lR88fqQ
YouTube2: http://www.youtube.com/watch?v=lglPJuBXVeE
YouTube3: http://www.youtube.com/watch?v=95RdGLFIbL8&list=PLQvWtv4LU5X05m_9X4xM-xNw03CpZoVtT

I don't pretend to be an A/C expert, but hopefully this will help a few folks w/ guidance and bravery to do their own. Anyone w/ questions or comments can contact me at "bobinyelm AT yahoo DOT com".

*Eric the Car Guy makes a few minor errors in nomenclature in his videos above, but they are "close enough" to get the job done.