I'm starting a new thread on my AC woes hoping that someone who has been in this situation has some input. My car has an obvious leak, verified by dye, at the expansion valve. The expansion valve clearly works because, when fully charged, I have very cold AC. I'm thinking about trying replacing the o-rings where the hoses connect to the expansion in the hope that one of them is the source of the leak. If the leak was on the evaporator side of the expansion valve, would it still cover the top of the transmission bell housing with dye? Or would the leak be directed inside under the dash? I've never had one of these apart and YouTube vids aren't very detailed.

 

Oops, just replied in your other thread while you were starting this thread. Copied message follows:


This video (complete with porno background music) shows some of the details of the valve:



Do you think the leak could be from one of the seals on the engine side? Those wouldn’t be too horrible to replace.

Have you checked for dye up under the dash?

 

I did check under the dash without doing any disassembly. I did not see any signs of dye under the dash. I think I'm going to roll the dice and pull the engine side connection, replace the o rings, and try it again. Maybe I'll wait a little longer to see if it holds vacuum but, after 20+ years in the chemical mfg industry, I know that sometimes you have a leak under pressure that you do not have under vacuum. Wish me luck. This car has pretty well beat the hell out of me but I love every second I'm driving it. When I hand it off to my daughter, I'm thinking there's going to have to be another Jag in the family for dad 😁

 

this should be the seal for your compressor plate. I put it in new on my old compressor only last year. Very soft and usable. Pm me an address and you can have it. My old one was hard as a rock and broke into pieces when removed. You should be able to do it without taking compressor off.

the expansion valve sealing ring could easily be your leak. It could be rock hard also. The other side of the valve is buried in the climate control cabinet and i doubt you would see a small leak without dash disassembly. I would definitely check the engine side first

i just remembered i bought a new expansion valve too in case mine was blocked. They should be the same but i cannot verify for sure. Anyway you are welcome to the whole unit or just the o rings. I can mail all o rings for nothing. If you want the entire valve i guess cheapest usps priority. Maybe 10 or 12 bucks. All parts i give you for nothing

just looked on the rockauto website where i got the valve. The valve i have is listed for your car also. The o rings should work

 

. Here is the piston and seal new

 

Very true. The vacuum test will also find most pressure leaks, but not all. Sometimes you get a loose piece of gasket that will seal in one direction under vacuum, but not in the other direction under pressure.

Don’t discount the old soapy water trick, either. When the system is charged but not running, you’d have approximately 70 PSI in the lines on a typical day. This is more than adequate for finding leaks using soapy water.

What if the system has just been reassembled, passes the vacuum test, but you’re hesitant to try refrigerant for a leak test? I’ve pressurized AC systems for a bubble leak test using argon from my MIG welder. It’s a lot cheaper and is nice and dry. Don't run it like that, but it’s fine for a static leak test and will be removed when you vacuum the system before filling with refrigerant.

Don't forget to clean up the old dye (aerosol electronic cleaner?) before refilling the system. You don’t want to be misled by old evidence from any repaired leaks.

Fingers crossed the firewall leak was from the seals on the engine side of the valve. They are exposed to multiple extreme heat/cool cycles. The seals under the dash lead a much more sheltered life and hopefully are fine.

 

Scottjh9,
I may take you up on that offer. I have an HVAC oring assortment that I may try first to see if I have the needed sizes.
Thanks to all for the advice and encouragement. If I can get the AC going and get the broken headlight adjusters fixed, I can hand it off to my kid who's going to love it.