Yay air conditioning!

Hello all in Jag land. Had A/C problems for the longest time. The culprit was supposed to be a blockage. Lady Luck is on my side today. I filled the system from 20lbs to 35lbs with r-134a and my temps went from 96F to 49F. I live in the dirty south where it’s almost always hot and humid. The wife will now take summer rides when the sun is out. Wanted to share the win!


So the question arises: Was it underfilled to begin with, or did some leak out?

Underfilling is very common. For a while there, it was all but impossible to find a shop that would properly charge an air conditioning circuit. I had to buy the connectors to top up my own to get it to cool properly.

There’s also the possibility that your condenser overheats – also very common, especially when the radiator fins get plugged up with tobacco and won’t let any air through. Then the freon circuit pressures skyrocket, and if there’s a pressure relief valve on there somewhere it pops open and wastes some of your R-134a to atmosphere. Then it never cools right again. You can usually tell because the relief valve has compressor oil all around it.

Of course, if you have a leak, well…

I look forward to hooking mine up again one day, with windows down and idling, I can feel the heat dissapating from the V12!
Are you still running the original GM compressor? I was going to buy the new aluminum version of it one day.


If his car is a '96. presumably he has a Sanden compressor.

Better than GM? I guess Ford didn’t want to give GM any business…

It’s a 96, and all original. The only leak point I can find is the low side valve. It’s apparent to the naked eye, and day-glow under uv. This is still day one, and hopefully not a bust soon after. Wish me luck fellas! And yes, I sat in the drivers seat at home with the air blowing cold and a cold beer enjoying the win!!!

PS (the condenser supposed was cleaned by previous owner. It looks okay to me, but I will still clean it out on my own…just haven’t reached that point in maintenance yet)


It’s not the condenser that’s usually the problem, it’s the radiator. Air has to flow through both, and the radiator has such tiny fins that they get all plugged up with grass clippings and whatnot. This prevents airflow through both the condenser and the rad.

Note also that fan issues cause just as much trouble for the condenser as for the engine. Make sure the fan clutch is good and the electric fan works. Your '96 probably doesn’t even run the electric fan until the freon pressure spikes; I would change that, but as is it shouldn’t hurt anything provided the fan works when the pressure rises.

Those ports were a problem for me. With the engine running and vibrations all around, the Schraeder valves would evidently bounce on their seats and leak, even though they appeared airtight when shut off. With R-12 this was easily fixed since the ports were standard AN fittings; I just screwed hard caps on them. When I converted to R-134a, the port adapters came with these cheesy plastic caps that wouldn’t seal diddlysquat. As mentioned before, I fixed the one on top by removing the adapter after finishing charging and screwing the AN hard cap back on. For the other, I found a metal screw that would thread into the center hole, and I installed it with an O-ring with a surrounding flat metal washer to keep the O-ring from being squished or blowing out. Reliably leak-free.

Phil …

“20lbs to 35lbs with r-134a” … You must have a REALLY big system :grinning:

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This is where, at a car wash, I’ll open the bonnet, and back-flush the radiators.

Often, if you pressure wash in the direction of air flow, ya just cram the bugs/grass/ tobacco in tighter.


Good idea, but all but impossible to actually accomplish – at least it was on my '83. Fan shroud was in the way. This is why it’s been my standing recommendation for some time that the radiator be removed every coolant change.

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The high and low pressure valves…the ones that look like schrader valves…they can be unscrewed to reveal an o-ring. Those do go bad and are simple to replace, however you must depressurize the system.

There’s a thread which explains how to recircuit your auxiliary fan so that it comes on whenever your air conditioner comes on. (It also comes on whenever it was originally designed to come on). I’ve done this. It’s pretty easy.

Actually, a guy at a shop showed me a cute little tool for replacing a Schraeder valve without depressurizing the system. It was a little glass container that screws onto the port, and there’s a rod in the end by which you can unscrew the old valve and screw in a new one under glass.

A leak in those Schraeder valves just never bothered me enough to do anything about it. It only leaks for a few seconds while you’re disconnecting your hoses and before you screw on the hard caps. You shouldn’t be relying on the Schraeder valves for long-term seal.

I have one of those, but it’s metal, not glass. You have to know what you’re doing. I’ve used mine once or twice but not recently (i.e. since I entered my seventies). I don’t think I’d be willing to chance not screwing up were I to need it again.

It’s a good practice IMO to squirt a little refrigeration oil into the valve before depressing it—for lubrication. I also apply a bit of that specialized refrigeration sealant onto the threads of the cap–I’ve seen them leak and fail to protect a leaking Schrader valve.

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If you’re relying on the threads to seal, you’re gonna be disappointed. The R-12 ports are AN fittings, sealed with a conical seat. The R-134a ports are sealed with an O-ring if they are sealed at all.

SAE flare fittings, but yes, a conical seat. Some of the caps try to match the seat, some rely in o-rings (as do all of the service fittings). In my experience the seats can use some help, regardless of what cap is used.