vanster

My rear ac has a leak which oil ends up in the passenger rear foot well
It's a slow leak but it leaks.
Question is if I only use the front which doesn't seem to leak and keep the rear off are the two then separate units?

EnBee

Sadly, no. The rear AC tees off the front high and low-pressure pipes at the firewall. There is an electronic solenoid under the passenger side rear seat in line with the high side pipe which controls flow through the rear evaporator, but the evaporator will still see low side and resting pressure when the solenoid is closed. Isolating the rear AC would involve cutting/capping these lines somehow.

I might have talked to you about getting to the rear AC unit if you were at Sharks in the Park last weekend... I talked to someone briefly who had oil pooling from the rear AC. Probably was you, but there is a pretty good chance you are not the only one with this problem! Anyhoo, there are some good write ups about getting to the rear unit if you can get your AC system evacuated. Hopefully it's just a leaky O-ring and not the evaporator, but I've read about other people having success with wicking in epoxy or JB weld under vacuum to repair a leaky evaporator.

vanster

Thanks
We did speak, but I don't think I asked you this question. What is the honest answer to evacuating the system? Why not just open it up and replace the O rings?

EnBee

Only needed if there is any residual freon in the system and if releasing it would make you feel bad. Given that the freon is probably all going to leak out one way or the other if you did nothing, you could probably just release any residual pressure and issue a silent apology to the ozone layer for your minor contribution to its damage. I certainly won't tell

But I have heard that some places will evacuate your r12 for free as long as they can keep it for resale (and if you haven't contaminated it with any "drop in" replacements). I have never tried this, as all my r12 leaked out long before I got the car. Anyway, AFAIK it's not a safety issue as long as you are not using your teeth to open the Schrader valve...

Mrmerlin

NOTE the rear evaporator has a mismatch of metals in its construction.

Copper lines are swaged into the aluminum of the core,
there is also some kind of setting putty used in this junction.

That said its best to clean the oil from these swages, use acetone.
then abrade them with a scotchbrite pad,

Make a dam with some blue tape and heat some JB weld in a microwave or heat gun,
and pour it into each dam let it cure ,
it should seal the crimps.

Use then new Green O rings in place of the old black ones.

NOTE if you plan to do any chemical flushing of the system,
make sure that this is done before you install new O rings ,
as the cleaning fluid will usually damage the o rings.
Also reseal the fuel cooler with fresh o rings

vanster

Got it
Thank you

dr bob

"oil in the rear passenger footwell" might steer me to the solenoid valve under the passenger's seat, and the o-ring seals there. There are also o-rings in the "bulkhead" fittings that pass refrigerant through the floor that can use attention. Oil tends to puddle at low spots in the system, so finding leaks at those places is easy to rationalize.

vanster

I just received a bag of O rings for the rear from Roger
Looks like I'm taking the seat out

Bilal928S4

I did a write up when I changed the AC O rings on my 90 or 91. It should be the same or similar for yours. Send me your email and I will send it to you if you don't find it through search.

Bill Ball

Bilal's write up is in posts 14 and 15 in this thread. i need it too. Thread has additional related info.

https://rennlist.com/forums/928-foru...placement.html