A/C O-RING locations

schmedes1 · 12-08-2005, 06:33 PM

I started to replace the R12 refrigerant in my 1989 944T about two months ago and after performing a vacuum pull, I saw (and smelled) freon gas blowing around the engine compartment -- maybe around the firewall but could not confirm. Anyway, I verified that the R12 system -- compressor et al -- are in good operational condition and will stay with R12 for now.

The repair manual is confusing on the number and location of o-rings required for the a/c system. Can anyone help with the details so I can be sure to replace all of the seals?? Not worried about source of parts, just where to put them.

rucool · 12-08-2005, 07:47 PM

If there is no dust around the joint, don't touch it, if there is then clean
of the mess , open the joint and replace the O ring, unless the system is losing gas within 12 months, don't go looking for any hidden joints,
there is more important things to be maintained on our cars.
R12 neoprene o rings last for years with R 134a

jtango · 12-09-2005, 05:21 AM

Is it possible to recharge an old r12 system with r1334a? Are there any mods that need to be done?

rucool · 12-09-2005, 11:03 AM

Flush the system with a flushing agent, change the compressor oil
to a polyester based oil, evacuate and re gas with R134a, also cange
the filter dryer canister.

jtango · 12-09-2005, 12:26 PM

Sounds good! It'll be a great spring time project. I know my system works but there is a leak as it stopped a few weeks after I had it charged. How do you change the compressor oil? Anyone had any luck with A/C sealers?

Porsche-O-Phile · Porsche-O-Phile's Garage

Remove compressor, drain oil by pouring it out. Then replace the oil with r-134a compatible oil, re-install the compressor & replace the receiver/drier (as has been mentioned) and associated o-rings. Evacuate system and charge up with r134a. Enjoy.

Zero10 · 12-09-2005, 04:49 PM

Hmm, O-rings.
There are 2 on the expansion valve. On late cars, you remove the heater blower, and cowl cover to get at it. There are 2 on the firewall, right behind the cam tower. Best of luck getting at those. They are for where the lines enter the passenger compartment. 2 O-rings on the receiver/dryer, 2 on the compressor itself. I can't recall now whether there are O-rings on the condensor... If there are, then there are 2 O-rings there as well.
That should be all of them. No idea on sizes, I just pull them, head over to partsource and match them up.

schmedes1 · 12-09-2005, 06:59 PM

Appreciate getting an answer to the original question!

jtango · 12-10-2005, 05:54 AM

Sorry, didn't mean to step on your thread! I was r134 and I got excited.

Zero10 · 12-10-2005, 06:55 PM

I was thinking about it, and I think they are a combination of #6, #8 and #10 A/C O-rings, but I am not 100% sure, I used a #8 and a #10 on the A/C compressor, but the receiver/dryer I bought had the O-rings in the package. I still don't remember if the condensor requires O-rings. I think it does, and they are both #10 if it does. Getting at the O-rings is the hardest part, as for the ones on the firewall, if you attempt it with the cam tower in place, you will wish that your hand could bend right in the middle of it, and an extra elbow would be nice. I tried it once... That reminds me of painful memories

If you are curious about converting the A/C system, you can essentially just drop in R134A, and it will _work_, but if you want it to be like new, get the whole shebang from Griffiths, the A/C compressor, and serpentine condensor. In order to keep pressures within specs, and keep the system as efficient as possible, a good condensor is essential, and serpentine condensors are superior in design to the typical row-type condensors our cars have. It's not a cheap conversion if you follow this, but it will be just like it was when the car rolled off the assembly line, but much more environmentally friendly.

In the case of my car, I used a R12 substitute (a hydrocarbon refrigerant), and am perfectly happy with it. It required no hardware changes, and it works very well. IMO it's the best bang-for-your-buck solution, and works almost as well as new.

R12 is expensive (and as I'm sure you know, bad for the environment), so use it wisely

Best of luck in the A/C system repair.