a319 air condition problem
One a319's cockpit and cabin temperature can not cool down.after checking find that pack1 and pack2 out temperature is 30¡æ. When set the hot air pushbutton to off the p1 and p2 pot is 0¡æ.After replace 24hk 25hk the failure is eliminated. Measure the 24hk and 25hk resistance .The valure is infinite.Can you explain it .And why set the hot air pushbutton to off the p1 and p2 become normal.thanks