Gary if you are replacing the r12 with r134 you are supposed to replace the black o rings with the green ones. i didnt change them on my convert. and havent had any problems but the other car that i am now putting together i am replacing all the o rings. i bought an o ring kit off ebay, it has all the sizes needed.
Doug, my idea was to eventually migrate to the r134 once I was ready for a/c again. I'm glad you responded before I put everything back together as now I can get the right o-rings before I reassemble. I did not know that there was a special set for the r-134. I'm sure you saved me and others a lot of rework and grief. Thank you!!! Gary
The old orings aren't necessarily incompatible with R134a, but they are very old and really should be replaced. Would you reuse an old oil filter seal? How about used 30yo heater hoses or belts. The green HBNR orings are just the next step in oring technology. Their development was brought about by the switch to R134a and new regulations about ambient leakage. They seal somewhat better than the old BNR orings and should be used in all mobile AC systems now. If you ask for "AC system orings" at the parts store, you'll get the green HBMR rings regardless of refrigerant. If you're rebuilding, cleaning and flushing an old system, leaving in the old orings would just be poor workmanship, especially considering the very small cost. When replacing the orings, be sure to get the proper diameter AND cross section as the old seals. Here's an example of a kit specifically for AC systems: https://www.ackits.com/pc/CP3011/Bu...1988+&+Prior+General+Motors+System+O-ring+Kit
Gary heres the kit i bought. http://cgi.ebay.com/ebaymotors/AUTO...mQQptZAutomotive_Services?hash=item3a5534717c
Thanks for the part numbers and leads on where to get the o-rings. I grabbed a universal kit at Autozone for $5.00 today. Once I get back into it in a week or so, I'll see how many I really need. I only want to do the components that are inside the a/c box for now so i can get it remounted. I'll worry about the other parts that I can access openly once I am ready for the cool breeze. Gary
Sounds like a plan! :TU: Good job testing and flushing, btw. You won't need any orings inside the box. Leave the TXV off until you decide to assemble the hoses and such. Make sure to cap off the open evap tubes to keep the small critters out. Spiders love small openings like that. Now would be a good time to have the TXV and POA valves tested and have the POA calibrated for the refrigerant you plan to use.
Thanks for the encouraging words. I actually never removed the TXV, but did disconnect and plug it during the cleaning. Can I just replace that o-ring for now and then plug everything after I remount the box? Would you happen to know where I could get an exploded drawing of the a/c box? I have several pictures of the disassembly process, but my shop manual cd does not seem to have the details of the box itself. There is a bunch of detail about the system and how everything hooks up, but nothing inside of the box. Thank you...Gary
Yes, you can replace that oring and then cap the open connections. For orings on AC systems, I use and recommend a product called Nylog. It's an oring lube and conditioner. If you can't find it locally, use silicone (dielectric tune up) grease to lube the orings and threaded fittings during assembly. As for the diagram of the box, sorry. I can't think of anywhere except the factory shop manual or assembly manual for that info. Google it, using various other similar GM vehicles and see what you can find. I'll bet someone, somewhere has posted it or made it available. I'll ask around and see if I know anyone with a manual or anything like that. Maybe someone else here has some ideas? Keep us posted on your progress.
