Very possible that the blower motor is on it's way out. Might also be loose or somthing may have fallen into it. Pull it out & have a look is the best way to find out.
Probably the heater blower motor.
somtimes a mouse moves into the blower motor and makes a nest ?
replace the blower motor resistor. it is located on the firewall near the heater hoses.
Probably a bad blower motor. Try tapping the blower motor gently with a hammer when it isn't working. It that makes it work, replace the blower motor.
There is a loose wire somewhere in the circuit - tapping the heater makes the wire complete the circuit !
depending on the vehicle, it could be the switch in the a/c control head unit or the reostat.which is usually located under the dash on the passenger side, on the blower motor housing.
could be a fuse, a relay, the blower motor or the blower resistor. It's easy to check the fuse, using the owners manual. I am not sure where the relay is, and it requires special tools or replacement with a known good relay to test. If the blower works on high and no other speed, then the resistor is bad. If fuse and relay are good, and blower does not work in any position, suspect the blower motor itself.
Your blower motor relay went bad. You may also need to replace either the blower motor or one of the climate control sensors. If your blower motor squeals or makes a scraping sound it is going bad and will damage the blower motor relay. JQ
could be a bad motor mount.mine was bad and I got a lot of vibrating / rattling sounds.
You have a loose connection. So when you hit a bump the connection makes contact, turning on the blower.
The clicking sound could be from your heater, a clock or other device.
If it is when you brake then there could be some loose hardware, if so tighten all the bolts that you can and if not when braking then it may be a ball joint.