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.

zaf
June 2010