anyone have a issue w/when weather gewts up in hi 90's 100's , truck wants to run hotter than normal and a/c just about quits working . is anyone done a complete flush to eliminate the hot issue ? fan clutch or add on elec fans might help but as long as its cool or normal outside in 80's or whatever I can live w/it but as soon as heat returns no a/c. very strange.
has anyone done a complete motor ,radiator flush , truck has 160000 miles and never had it done . any knowledgeable help appreciated very much!!!

I live in Phoenix and my 1988 B2200 AC does fine. Yes, in 2003 I did a chemical cooling system flush, some Prestone flush available at the auto store, then flushed with water a few times and added a new thermostat. What I think your main issue is: a bad fan clutch. I have replaced mine twice in the 10 years I've owned the truck, this affects AC condenser cooling as well, and may be bad even if your temperature gauge reads in the OK range. My fan clutch was a Hayden lifetime warranty from Pep Boys; on the AC boards the guys there say to use "factory" fan clutches only, but my replacement was free (my labor, not bad). I also found a small leakage of air that went over the heater core, so I bypass the heater core at the firewall with a short length of hose and hose clamps, then re-connect in the fall, helps even more. So the issue may be slightly other than the AC system itself. I'm assuming at this point that you still have R12 refrigerant (proper amount) and that your compressor/AC pressures are OK.

The AC complaint should not be related to the engine temperature except as an incidental thing.

How hot is is the truck running? Does it boil over or cause you to lose coolant out the reservoir? Have you drained some coolant from the radiator and visually inspected it? Have you measured the coolant temp? What is it?

Have you measured the air temp coming out of the vents when the AC is on high and set to recirculate? What is it?

If you want to flush the engine you can buy a kit from the parts house that'll help make it a painless operation, but try to avoid possibly wasting a lot of time and/or money trying to fix something unless you're sure that it's actually the source of the problem.

Yes, an overheating engine can be completely unrelated to the AC malfunction. BUT, a bad fan clutch can be a single cause of both, needs to be checked out. One way, with engine hot (but OFF), spin the fan by hand - there should be considerable resistance, it should not spin freely. I've replaced my fan clutch twice in 10 years, they don't last forever. This is a common malfunction often overlooked as detailed on the air-conditioning boards http://forum.acsource.net/ or http://www.autoacforum.com/

Cusser is correct. But it also needs to be kept in mind that the clutch allows the fan to basically freewheel at highway speeds.