Diagrams of a 2001 Ford F150 AC system can be purchased at any auto parts store. If the store does not have it in stock, it can be special ordered.
You probably have a leaking heater core.
Flush the cooling system? Flush the fuel system? Flush the hydraulic brake system? Flush the AC system? Flush the transmission? Pick one.
134a
yes,a good parts man will give you a belt to bypass your ac.
You use an AC Flush & Purge machine, if you don't have one of those then you disassemble the entire system and used compressed air with flush solvent to clean the system. NOTE: trying to flush the system with compressed air is not recommended as it is very ineffective.
left side on firewall should be on the side of ac condencer
r134 should be about 2 lb
If there is metal chips and trash from the old compressor in the system, yes you need to flush the system. Any trash left in the system will shorten the life of the new pump.
The AC port for a 1999 Ford F150 is in the back of the engine compartment near the firewall. It is the larger of the two hoses going to the compressor.
On the receiver/dryer.
Take it to a Ford Dealer.