Converted ny 89' 740T to 134a last night. WHOW! After goin all summer long w/o A/C in North Carolina I would appreciate any cooling at all. The results:

Idle 39-40 F

60-70mph 33-36 F

Ambient conditions: 73 F 60% RH

I could see my breath while driving. I believe I may have started to freeze up the evaporator by the time I got to work this morning.

I didn't do anything special. In fact i cut a few corners. I did not drain all the old oil out of the compressor (lazy). I put a vacuum on the old R12 system to draw out as much contaminates as possible and not pull them thru the new components. Then I opened the system and fitted the new 134a parts. The most difficult part was removing the old orifice, just wiggle back and forth for several minutes and it will eventually come out. Be careful after you fill the receiver with the ester oil as it will spill out if you tilt the receiver very much(I made a mess). I also didn't have a new O-ring for the new filler valve so I used the old one - time will tell if this will cause a problem. After all fittings tight I put a vacuum on the system, could only get about 20 mm HG for about 30 minutes (impatient). I then shut off the valve to isolate the vacuum on the system to see if the system was tight - vacuum held firm. I charged the system with three cans of 134a (36 oz)plus a 2 oz can of ester oil since I spilled so much of the oil supplied with the kit. The performance as indicated above is outstanding, maybe I just got lucky considering the corners I cut. Will give update on performance in a few weeks.