99 ford ranger AC

My 99 Ranger ac stops blowing when the engine is under a load. It works fine otherwise. What’s the fix?

Does it stop blowing or does it start blowing out the defrost or heat vents? If it coming out the defrost or heat vents, check for vacuumm leaks to the AC controls and to the actuators.

It stops blowing all together…till I let off the throttle.