Originally Posted by haigha

Certainly a likely cause. First, make sure you have the wheel in the middle of the center vent set to all the way to the cold side (blue dots).

Here's a thread with useful info I found with the following google search hi and low gauge pressure ac e53 site:xoutpost.com

https://xoutpost.com/bmw-sav-forums/...ure-specs.html

See info in post #7 for example:

Once you get the gauges hooked up, the low side should be somewhere between 25 - 35 psi, and the high side somewhere between 200 - 300 psi, varies with environmental conditions as you know. Also, for example, if your aux fan stops working, the high side pressure can shoot up to 450 psi with a quickness. Its amazing what effect it has on the head pressure....

If the pressures are off, like the low side is 45 psi or higher, etc. Then there is likely a problem with an ac component and would need repairs. If its low, even just a hair low, then it probably has a leak somewhere. I'd bring it somewhere with an "automatic" ac machine. It essentially is set to recover, vacuum (which removes any moisture from the system) and fill to the proper charge level. No over or under filling with this setup, which is highly recommended with a vehicle so temperamental to its charge level as one that takes just a smidge under a pound... even an experienced indy with his gauges and a can hanging off of them can't properly judge the correct amount on these

Personally, I've had success with AC Pro from Walmart that comes with a simple gauge for the low side. I squeeze the trigger for about 5 seconds and then check the temp at the center vent with an infrared gun. Repeat that until it gets to about 45 F. The gauge on the AC Pro gets to about two-thirds of the green zone at this point. That may vary with the outside temperature. I usually fill it when it's between 80 and 90 F here.

https://www.walmart.com/ip/A-C-Pro-A...0-oz/353326131

I have to add some each spring. Used to be every other year and now it's every year. Mine is 19 years old and rubber gets dried out in the southwest.