83na944

Greg,
Thanks for the warning. I never considered that the can might explode, but I was smart enough to check the pressure in the system and the can. I knew that I didn't want the system pressure to be higher because the Freon would flow into the can, and that was not what I was trying to do.

I'll remove the schraeder valve core before attaching the "L" adapter. I guess I should flush the system before adding R134a, right. Do you have any suggestions about the best place to open the system to flush?

Thanks,
Steve

Greg86andahalf

Steve,

Back in the day, shops flushed entire closed systems with R12 using both the high and low service ports. That's no longer doable and the system flush solvents sold today make it possible for only certain components to be flushed. The condenser, evaporator, lines and hoses can be flushed. The expansion valve, drier and compressor should not be flushed. You will be (should be) replacing the drier, so that's not a problem. The expansion valve on your car, according to the WSM, is a PITA to get to and requires removal of the HVAC unit inside the car.

Therefore, I would flush only the condenser with a flush solvent kit. If you can, pull the condenser and clean the fins to remove all road stones and debris, then run a garden hose through the fins in both directions. Do the same with the radiator. You may be surprised how much better your AC cools and your engine may even run cooler too once maximum airflow over the condenser and radiator is restored.

Replace every O-ring you can reach and replace the drier with a new one.
Pull a long, deep vacuum, check for leaks and charge into the vacuum with R134a to 80% by weight of the spec for R12. You may still see bubbles in the drier window when the system is fully charged with R12. Ignore the window!! and use a R134a manifold gauge set to verify the highand low working peressures.

Greg

83na944

Greg,

Thanks for the great advice.

Yea, I really didn't want to go after the expansion valve. There is enough R12 still left to keep the pressure switch going and the system cools some, so the expansion valve is working.

I plan to have someone suck the R12 out, clean the condensor, put in new the "O" rings with a bit of Nylog, put drain the compressor, put in ester oil, slip on an adapter, pull a vacuum on it for a while, and finally charge with the "ozone-friendly" R134a.

Thanks,
Steve

Porsche-O-Phile

Thanks everyone for your input; this has been an extremely educational and informative thread. I'll let you all know how the compressor / lines replacement goes. Much appreciated.

BTW anyone in SoCal know where to get these O-rings and / or what sizes & quantities I'll need? I don't feel like having to run to the store once everything is torn apart; I'd MUCH prefer to have all the tools & parts ahead of time for a quality, last-the-lifetime-of-the-car kind of job. I believe in "fix it once - correctly".

sm

Have you had a chance to replace the A/C hoses yet? Is it even possible with the motor still in the car?

Porsche-O-Phile

Not yet; I'm pretty sure it can be done but it may require removal of the dashboard. I don't have the facilities to remove the engine, so that's not an option, even if it is theoretically easier (and would enable me to repair other things while I'm in there).

I ended up getting a Sanden 134a compressor from 944 online, so I'll keep you posted on how it works. They seem to be VERY highly rated though.

a.n.other

I ordered a set of o-rings from www.ackits.com - only $7 or so for loads of green O-rings. I got the GM assorted O-ring kit on the advice of the people there after i gave them the sizes from PET and the year (84) and model of my car. They seemed really helpful, but i cannot vouch for how well they fit because i haven't got round to fitting them yet.

I needed 8 O-rings according to PET - cannot remember the sizes, but can find out if you need.