blown455sd

Long mod list, I'll shorten as best I can .Just want to give you an idea where to start.
I had a A/C compressor go bad and while I knew not to turn on the A/C while driving, one of my kids did not. And smoked the serpentine belt. To make matters worse, they continued to drive it the rest of the night until she quit from lack of battery power.
Changed out the compressor and evac'd and charged the A/C. ..Ice Cold
Over the course of a couple months I was battling overheating issues... I knew what had happened.
Ordered a Edelbrock Head, ARP bolts, Gaskets ect.
While doing the head swap I also upgraded the waterpump with a Flowkooler, Hesco thermostat housing, OEM replacement radiator, Thermostat, Temp Sending Unit. Hoses and new Belt.
While breaking in the new valvetrain I was constantly in and out of the car keeping an eye on the gauges with the A/C on.
I was getting some help diagnosing a stumble I still had from a buddy with a live data tool and I noticed the Aux fan was not coming on with temp. I've since learned it comes on at 218 degrees or so. So I wouldn't see it coming on at 210 like I thought. To check the fan, I pulled the plug on the Tstat housing and the Fan came on as it's supposed too.
Now, all of a sudden I have no A/C. The compressor is not locking up nor is the fan engaging. I have swapped relays, checked fuses in the underhood DB. All good.
Jumpered the plug on the evac canister and the A/C compressor locks up for a second then disengages.
Other than being low on refrigerant , what am I not checking ? I could see losing a/c gradually if I had a leak, but that didn't happen. Just all of a sudden.

Suggestions...Advice

As always , Thanks in advance