I posted another thread and I had lots of questions and misconceptions about the aux fans relationship. With no disrespect to those that helped me (thanks), I just want to share what worked for me.

My compressor clutch engaged
My aux fan was working
My A/C was not blowing cold
never had an issue or charge in 10 years
2004 X5, 3.0, 150k

I bought a manifold at Harbor freight (about $45), (searched on my iPhone for a coupon - he scanned the coupon off the screen and it took 20% off).
bought a "can tap"($6) which allows you to attach the coolant to the manifold tester and bought a can of leak seal R-134a ($15).

My weather turned chilly, tested the pressures on a day of 50 degrees and then on a 60 degree day. Didn't really get pressures that were too off of the charts (google R-134a pressure chart) , the aux fan would not stay on steady, so high side fluctuated.

Finally a day I could work on it, 72 degrees outside, had 2 digital thermostats plus the car saying 72. Car warmed up, A/C on high, aux fan running, clutch spinning.

according to the charts at 70 degrees low side should be 35-40, high at 145-160.

I was going to shoot for a low side of 40 (figuring it was a little warmer than 70). When I let the coolant flow into the low side the meter jumped high quick - I got scared, shut it down - pressure stabilized at around the 30, then I opened it slowly, I knew coolant was flowing the can got cold and low side rose to 35 and high was at 205.
It would not take any more, no rise on the low side above 35.
My A/C is blowing cold, I am happy with the results

My point is, my system is not acting according to the charts, low side is on the low side and high side is higher than the charts. But I am 3 days into a working A/C. Maybe not a permeant fix as I may have a leek but if I had to add a little every summer season - no big deal. (don't tell the EPA)

I read ALOT about a/c pressures and still don't understand it. I am just sharing my experience.
I think if I did it over I would just buy the coolant/meter setup and just worry about the low side.

good luck and hope this helps someone else