I drive a 2005 Freighliner w700 panel van for work. It is equipped with air conditioning. the problem is that the air only comes out of the vents in a trickle. the fan is not the problem - it works fine. when the problem first began, i heard a "zzzt" noise from the ar ea of the fuse box - like something shorted out. However, i can find anything shorted out. It seems that whatever the mechanism is that directs the airflow to the vents has failed. Can you help please??

Optional Information:
2005

Already Tried:
looking in relay panel for "air relay"