nd set it to max cold and with it on recirculate. set the fan speed on medium. for AUTO a.c. disregard. close all the doors and windows except the drivers window, leave it about 1/2 inch open. now you start watching the gauges for psi. readings. let the vehicle run for about 20 minutes to let the inside cool down some. if the low side reading are 0 psi. to 20 psi. then add a little freon to get th