I went back to my buddy's today and after de-greasing all of my pulleys and installing a new belt yesterday, he charged the system back up with 3.6 lbs of R134a. This time the compressor operated as expected. No belt slippage, no noises, no compressor lock-up..... everything seemed fine. However, as mild as it was outside today (64 degrees at the time of the testing), in the shade, I let the car idle for 20 minutes with the front and rear A/C on the coldest setting, on recirc mode, with the blower motors on full-blast. Got a best of 56 degrees outlet temperature of around the 17 minute mark. The compressor stayed running the whole time-- it did not cycle off, while I left the car idling and watching the pressures on the A/C machine. Again, only 64 degrees outside, so the inside of the car was absolutely not hot at all. He jumped in the car after the 20 mins and held the engine at around 2,500 RPM for 4 mins or so. The outlet temp finally jumped down to around 51 degrees and settled there before he decided to let off the throttle. Here's a video of the pressures while he held the engine at around 2,500 RPM:https://www.youtube.com/watch?v=EbWZULU0krE
We did spray some water on the condenser after this. We didn't exactly mist the water, and couldn't because his garden hose nozzle wouldn't mist, but after spraying one side of the condenser down a little the high side pressure did from drop around 175 PSI to under 150 PSI. I'm not exactly sure what that indicates, but here's a video of it. The video started literally like one second after he started spraying the condenser:https://www.youtube.com/watch?v=jh4xv424Rpw
Outlet temp had increased while we went and got the hose out to do this, and it dropped back down to around 56 degrees after spraying the condenser.
Still under 65 degrees ambient temperature, I headed home down the highway after this. Still a comfortable temperature in the cabin (around 71-72 degrees) yet after 10 mins of driving down the highway with the A/C still on full-blast, the best I was getting was around 49 degrees outlet temperature. After having been driving down the highway 20 more minutes later, the best I ever say was 47.2 degrees. Every time I came to a stop, the temps would creep up to around 50 degrees. Honestly, if anyone tells me that's an OK temperature based on the ambient temperature and the cabin temperature..... I can't agree with that. Once it gets in the 80s and higher again, the car will be back to putting out around 62-65 degrees out of the vents while idling for a while, and MAYBE 53 degrees at best when doing normal, non-highway driving. Nothing unfortunately seems to have improved after installing this new Motorcraft compressor, aside from the clutch bearing not squeaking at times like the last one was doing after a couple of years. At a loss again with this thing.
Another buddy of mine was a technician at a Ford dealer for several years, and now has his own shop working primarily on late model Fords. He has serviced the A/C systems of several '03-'06 Expeditions and Navigators, and has been stumped by my outlet temperatures as well. He has never replaced the extent of A/C components I have replaced on any of the vehicles he has worked on, but he understands the A/C systems pretty well and has always seen sub-40-degree outlet temperatures out of them. He knows exactly what I've done each time I've replaced parts, flushed the system, did a deep vacuum, re-filled the system (he has filled it a few other times).... and concurs that everything I've done was done the best way possible. I guess one could argue using a scale instead of an A/C machine would be more accurate, but his A/C machines uses a built-in calibrated scale under the 30 lb refrigerant tank, in order to gauge how much refrigerant to add.
So once again, I'm at a total loss lol. And the problem is with the front AND rear A/C systems.... so to me, the problem must reside with a common part, such as the condenser, compressor, accumulator/drier, or muffler...... rather than expansion valves, blend door issues, evaporator issues, other plenum issues, etc.