The 134A #'s are not drastically different. Good luck finding 40 on a '04-up NB. Some people actually report nice cold AC in 'em but i think they'd lie about other things too. LOL I've had acouple of interesting experiences charging cars with electric fans when the fan wasn't operating and one of 'em was a BMW that had a multi blade engine fan but the aux. electric in front of the radiator wasn't working. Talk about soaring pressures!
There are actually a few cars that still had sight glasses up till recent years. Don't know if any of those cars still do or not. Did make adding a little pretty easy (when that was still legal).

 

R134a is no where near as good as R12. Just wish they wouldn't sell R134a in stores to just anyone... seems like a good way for someone to destroy their a/c.

 

The epa requires a cfc liscense to purchase or handle refrigerants. There's a reason, why anyone has access to be able to work on systems without a liscense is beyond me.

 

Got a manifold gauge set, thermometer, and a 12.3 oz can of R134a with UV leak detector.

Started the engine and the low pressure side was 25 PSI with 73° ambient temps. A/C was holding steady @ 50°. High pressure side was 150 PSI. I ended up adding the whole can (total added now is 32.3 oz on a system capacity of 34 oz.

Low side pressure went up to 35 and would go no higher. High side pressure went up to 160 and no higher. Compressor still runs continuously.

It seems I have a substantial leak somewhere once pressures reach those levels, as I've added enough refrigerant now to very nearly recharge the entire system from empty. I'll drive it a day or two and then start looking for the UV dye.

 

It won't take long. Don't wait too long or the dye will be every where and you won't be able to tell where it came from.

 

Waiting on a UV light and glasses to get here from Amazon. Truck has been sitting in my garage since I discovered the driver front brake caliper was seizing....

New calipers, pads, and stainless braided brake lines are here. I've just got to find time to work on it now....

 

UV light and glasses got here. The dye is very visible, glows brightly even with the shop lights on and not using the glasses. I can see it on the low pressure port, which is to be expected because I added it not long ago.

Using the glasses in a dark garage, I found no leaks. My guess is evap core? I would think I should be able to see something from the cab, but??? I haven't driven the truck because of a brake problem, but that's getting solved later this week when I get time. Maybe drive with the A/C for a couple days and check again?

 

I would drive it then for a few days allowing the system to build higher pressures. If there is nothing in the engine compartment after that I would suspect the evap coil. Stupid question, do you have all your caps on the ports?

 

Yes. The dye I saw on the low pressure port was confined under the cap, so I hope it was just from the fill.