2003 Buick Rendezvous heater blower

There is no ac/heater blowing at all, very small amount of heat coming out of the defrost/regardless of setting, checked fuses, and they were fine, there is a clicking sound like it wants to work, but it doesn't, however it was working in the morning, but went to lunch and nothing, do you have any suggestions of what might cause this problem and were do I start,

Thank-you in advance