Check for debris stuck between the ac condenser and the radiator such as leaves.
Alaska
No, exhaust does not have enough oxygen in it for the engine to run.
Any air compressor that can achieve and hold 100psi will run an air gun. the larger the tank the more lugs you can remove before the compressor will need to run again.
Yes, if the air pocket is large enough to prevent proper coolant circulation.
She was never run over by a truck.
You can adjust the idle air control valve on a 1992 1500 truck while it is just idling. This is done if the truck is idling too fast or too slow. It will help the truck run better.
Canada
Anytime the A/C is on the fan should run continuously. If not then the fan is bad, fuse blown, or the relay is bad.
It takes 3 things for the engine to run. Fuel, spark, & air. You have air, and the truck turns over so you are missing either spark or fuel. You have to find out which of those you are missing.
Running the AC compressor uses horsepower, and the truck does not have enough to overcome the loss.
Low coolantPlugged or restricted radiatorBad thermostatBad water pumpDefective radiator capSystem airbound
Check the operation of the cooling fan or fans. One should run constantly with the A/C on. If it does not, check the fuse, relay, and finally the fan itself.