As I said before, the flasher relay is imbedded in the hazzard switch. When the relay fails, neither the flasher nor the turn signals will work. Because the turn signals sometime work, you can rule out the fuse. Because the turn signal light comes on in the instrument cluster, you can rule out the switch on the stalk. That leaves the relay at fault, which means that you need a new hazzard switch.

The relay may work sometimes, depending on cabin temperature. In the meantime, I sugggest moving the turn signal stalk manually to indicate a turn to the other cars.