Tony

Thanks Dave...
another development now.
It appears what was glowing around the brazed joints was hardened residue/material from the leaking expansion valve. ?? It flaked off in a few chunks. Gawd knows what may have been spilled down there in the last 32 yrs.. I just cleaned the rear evaporator and MacGyvered a vacuum set up with a mighty vac. Ugly and my hand hurts from pumping it, but a managed to get 24 inches and it has stayed there for the last few hours.

Seems the the rear expansion valve Orings are the culprit after all.

i also managed to block the rear lines and drew vacuum on the rest of the system.....it holds....no leaks.

I may be in luck in the end.


Crude but there appears to be no leaks in the core.

worf928

This post should probably be in your other thread...
Maybe. If it holds "sore hand" vacuum it doesn't mean that it will hold *pressure.* You might want to 'reverse' your setup and pressurize the evaporator and use the 'soapy bubble' diagnostic process. The evap is part of the low-pressure part of the system, so 90-ish PSI should be as much pressure as it ever sees. I wouldn't go above that.

Captain Earl has frequently told me stories about leaking rear evaporators. He ...

... MacGyvered a setup functionally similar to yours. What he'd do was put a coating of JB-Weld around the copper-to-aluminum joints and then use his A/C vacuum pump to "pull" the JB-Weld into the joints. He claims great success with this process.

I have such a setup, using an old expansion valve, that lets me either pressurize or vacuum a rear evaporator. But, I use my A/C vacuum pump for the latter. So far with my gizmo, operational only in the last year, I've found one leaking rear evap. But, that one was bypassed as above.

Bigfoot928

in looking at my engine bay and more pics with the engine removed, if you want to remove the rear air, you can cut the lines under the car, and remove the ac lines with the engine in the car. Installing new lines without rear air can be done with the engine in the car. It's a pain but it can be done. the engine harness does need to be moved,

dr bob

Were I looking seriously at a rear-air delete or disable. I'd be tempted to make block-offs that fit under the seat, and replace the inside half of the bulkhead pass-throughs where the hardlines pass through the floor under the right front seat. That way the system could be easily restored in the future.