Recently got in my car a few days ago and my ac was not blowing air. Previously in the morning the vehicle was used and everything was normal. A few hours later, and for the next few days the ac system worked as normal. Got in my car today and suddenly no air again. Help!
You have either a bad fan "HVAC blower" motor, or more likely, a blown speed controller - likely a simple resistor pack.
Does the fan work on the highest "MAX" setting? If so, that's a sure sign of a bad blower motor resistor pack. The highest setting bypasses the resistor pack as a failsafe - so that you should always have a working fan for a defrost "emergency".
They are inexpensive and easy to replace, although being a small child or physically petite person helps. The part is located under the glovebox, mounted near the firewall on a bracket just to the left of the blower motor. My 235 lbs. has done dozens of these, but I always wake up sore.
The next time it stops working, make certain the fan is turned "on" and get up under and wiggle the wires depicted in the above photo, including the wires on the side of the fan motor. It's possible there's a loose connection.
Also, rap/bang on the motor case slightly, and if the fan starts blowing it's because there is a deadspot on the armature. In this case, the blower will have to be replaced,