A/c and heaters stop Au1 Fairmont

[trublu1]

Hi,a friend of mine borrowed my Au1 Fairmont for a quick trip but when he brought it back he said that the a/c didnt work,though it was working great several hours before he took it (as was the heaters), i then had a look to see what the problem could be and i then found out that the heaters were not working as well.The fan and everything else works except the a/c and heater.Does anyone have any idea what could be wrong?