no cycla autovent 4000

good day to all, I have a problem with an emergency ventilator autovent 4000, I have looked for technical information of this team and nothing, I ask for your help to solve the problem, do not cycle, to put the breaths per minute 9, 1 sec child, volume tidal 400 ml, does not work, I increase the breaths per minute to 12 and work but irregularly, increase to 14 and respirations shoot at higher speed, return the selector to 12 and reduce breaths, someone can help me with information or some tip, the equipment is totally pneumatic nothing of electronics. Thank you for your attention. regards my email floresr_kco@hotmail.com