94 22re truck airconditioning cuts off at idle?

94 22re truck airconditioning cuts off at idle?
there is a thing called an air conditioning amplifier. you need to pull out the glove box( 3 phillips screws at the top of the glove box, when you open it. 1 phillips screw on the lower left, on the outside of the glove box. and a 10mm bolt on the right lower outside of the box. then pull it down and out, from the top part of the glove box. you'll need to unplug the speaker too.).
at the top of the top of where the ducting and fan are( in the upper part of behind where the glove box is ). you'll see a rectangle plug. shine a light to the right of the plug. about 1/2 inch. you'll see a small round knob and an arc'd arrow, with an H and L on each side. turn the knob all the way to the L. that knob chooses the rpm of the engine, to cut off the a/c. its suppose to help keep your engine from bogging down at idle. by shutting off the a/c and letting the engine idle freely. with the knob turned to the L all the way. your a/c should stay on all the time, when switched on. you can contact me at isettacruiser@hotmail.com, for any more help.