You need to connect gauges and see if the charge is low. It never hurts to check fuses before hand.
With a low charge the low pressure switch will not activate the compressor clutch. This prevents compressor damage.
If the system works in economy mode making the blower motor come on, it is probably low on refrigerant. If you have no gauges or experience in refrigeration, you either need to invest in equipment and study, or take it to a pro.