Left directional lights work about 50% of the time. The other 50% the flasher clicks rapidly but no lights work.
The right directionals work all the time, as do the hazards (same flasher unit for the hazards).
Doesn’t seem to me that the flasher unit could be the problem, but what is? Bad ground somewhere on the left? Poor left bulb connection? Bulb “going bad”? This has been happening for a couple of weeks.
There could be a bad ground or perhaps faulty bulbs or faulty bulb sockets.
If the bulbs have a double filament in them, the wires may be touching each other.
Replace the bulbs first, they don’t cost much. Next, clean the ground contacts in the bulb sockets.
You MAY have to check for faulty/corroded wiring connections behind the bulb sockets too.
Other than agreeing with Roadrunner about the bulb filaments touching there is something else related to the bulbs that can cause this.
Over time vibration (not noticeable to the driver) in the car can wallow out the lead contacts on the bulbs. Instead of being dome shaped they will develop a concave area in the middle of the contact. This leads to either a poor contact or a high resistance in the circuit. High resistance causes the flasher to sense more of a load than what really exists and this in turn causes the rapid blinking.
For some reason I’ve seen this on Subaru more than other makes of cars but have never taken the time to sit down and figure out why.