At wits end with air conditioning

[ScottD]

The last thing I have to fix on my 86 GLHS is the air conditioning.

I have replaced everything in the system including:

Evaporator (aftermarket)
Receiver/Drier (aftermarket)
Condensor (aftermarket)
Compressor (rebuilt)
H-valve (aftermarket)
Lines (NOS Mopar)
Schrader valves (aftermarket)

I have installed new crush seals. I oiled them and torqued each to spec. I have sanded and make sure all the line fittings where the gaskets go are nice and clean. I've done this a couple of times now, using the min torque specs, and then the max (the FSM gives a range).

No matter what I do, when I pull vacuum on the system I am seeing 29 in of vac, which is good, however, when I close the vacuum manifold gauges, it won't hold vacuum. It just slowly leaks down.

What am I missing? I'm pretty frustrated at this point.

[Pat]

Total stab in the dark here, but are you sure you're not leaking through your gauge?

[ScottD]

Total stab in the dark here, but are you sure you're not leaking through your gauge?

I pulled vac on just the gauge and closed it off and it held, so I believe the manifold gauge is not the issue.

[bigbarneycars]

You need to get some dye in the system to find the leak Scott. Me? I bite the bullet on that one. R -12 leak can be found with a Sound sensor, R-134 has to be found Visually, Jer

[RoadWarrior222]

How many valves/ports do you have in the system, those things often don't seal until they have a few PSI of pressure behind them.... i.e. if you were filling it realllll slow, they wouldn't snap closed... so I can imagine them leaking vacuum also.

[RoadWarrior222]

Exactly how fast is it leaking down? You may be experiencing a phenomenon known as "outgassing" where all the air and water adsorbed into the surfaces gets slowly released. To thoroughly outgas a vacuum system takes hours of pulling vacuum on it. Also if you've got the oil in there already, or if there's oil residue, you're pretty much just slowly vaporising it.

So if you just pull vacuum on it for a few mins, then see the gauge drop over an hour or so, you might not have a leak, might just be liberating gas from something... and it sucks it back in or recondenses in the case of oil or water every time you crack it open.

[shadow88]

Nitrogen pressure test and spray soapy water to look for leaks.

[wallace]

Diamonds to doorknobs it is the two connections at the filter/drier if they are the single bolt ones with a flat gasket. I fought the same issue on my dd and that was the problem. The fix is to get the lines off of a Chrysler Imperial it will have threaded connections at the filter/drier. have the ends put on your existing lines and use the Imperial drier. Good luck.

[ScottD]

It is leaking down fairly quickly.

One difference in the system is the evaporator, the fittings are different. Instead of the connection being female they are male and go into the H-valve. I don't think this would make a difference.

I've read the drier connections can be problematic. I saw in another post someone suggested using HBNR o-rings at the drier.

[RoadWarrior222]

"Fairly quickly" sounds more like a leak then, unless there's any chance of liquid water in there.

[black86glhs]

I wonder if the seals in the lines on the gauge set are leaking. Specifically at the ends where they attach to the car. I have had that happen before. If you don't have nitrogen available(not many do) you can use small cans of R-134 to find the leak. If you find it quickly, it is cheap. If you are converting over to R-134, you'll just need a couple extra cans. Oh yeah and a can of dye.

[ScottD]

I am converting it to R134.

I had AC issues on my Spirit R/T, put new lines on, swapped in a new receiver/drier, and had to do so some clean up on the gasket surfaces to get it to seal. But it did eventually seal and hold vacuum with the same manifold gauge set I'm using now.

[OnLooker]

Nitrogen pressure test and spray soapy water to look for leaks.

This is your best bet.

[wheming]

Are you attached to both high and low side when drawing vacuum?
If not, you could have a bad schraeder valve seal. Not uncommon to get a bad one new.

If it had refrigerant in the system I'd say leave the vacation pump on overnight, but you replaced everything. So it should hold vacation. Before you charge it for good, after you find your leak, leave the vacation pump on overnight to get all the moisture out.
You can also try pre-oiling your o-rings and gaskets.

[black86glhs]

I am converting it to R134.

I had AC issues on my Spirit R/T, put new lines on, swapped in a new receiver/drier, and had to do so some clean up on the gasket surfaces to get it to seal. But it did eventually seal and hold vacuum with the same manifold gauge set I'm using now.

Gotcha. You know more about it than I do apparently....lol. You could try the O-rings you mentioned. I do know if the surfaces aren't really smooth, they won't seal.
Can you make an adapter that you bolt in place of the compressor and the valve near the evap to rule out them leaking?

[shackwrrr]

Just spurt some 134 in there and the leak should show up quick. Without nitrogen that's about all you can do.

[ScottD]

Are you attached to both high and low side when drawing vacuum?
If not, you could have a bad schraeder valve seal. Not uncommon to get a bad one new.

If it had refrigerant in the system I'd say leave the vacation pump on overnight, but you replaced everything. So it should hold vacation. Before you charge it for good, after you find your leak, leave the vacation pump on overnight to get all the moisture out.
You can also try pre-oiling your o-rings and gaskets.

I did pre-oil the gaskets this time. I may have more new schrader valves, I thought about that too.

Gotcha. You know more about it than I do apparently....lol. You could try the O-rings you mentioned. I do know if the surfaces aren't really smooth, they won't seal.
Can you make an adapter that you bolt in place of the compressor and the valve near the evap to rule out them leaking?

I have all the mating surfaces really clean and smooth at this point. I'm thinking about the o-rings but at the same time the same fittings are on my R/T and I was able to get them to seal.

Just spurt some 134 in there and the leak should show up quick. Without nitrogen that's about all you can do.

I'm starting to think this is probably my best option. Thanks for all the responses.

[wheming]

Hey, I see why you are frustrated! Hopefully it wont be a leak in your new evaporator.

I probably have all the same to look forward to when I install all the new a/c parts in Mini.

[black86glhs]

Took me 2 months to finally get my Intrigue to seal when I replaced all the components on it. Even after replacing all the o-rings, I had to test each fitting until I found one that was leaking and had to replace 2 of the o-rings again. That finally got it.
I know it is frustrating.

[ScottD]

On the low side port, which is on the compressor, when you put the adapter in, do you remove the schrader valve that is in the male fitting in the compressor, thus leaving only the schrader valve that is in the adapter itself?