how to sort my heating/air con out?

on my ford focus lx 1.8,the heater was only blowing on number 4 so gat the resistor replaced as it was burnt out.this improved it slightly by blowing air on number 2 3 and 4.all be it the heat is always warm.not sure if i need a heater motor or what?also the air con button lights up when pressed but not working.might just need gassing or might be summat else,can anyone advise me many thanks.