Q: air conditioning

So my air conditioning hasn't been working right.. it had when out.. my uncle fixed it but when he fixed it, he fixed it to where it would turn on and off but would have to be plugged in and unplugged from under the dashboard. my fan doesn't turn on and of by the knobs. it went out again. my uncle had to replace my alternator and for some reason my air conditioning started working again but still had to be plugged in and unplugged from the under the dashboard. when ever I hit a bump or sometimes don't hit a bump the fan make this rattling sound and the vibration is hard to where you feel it on the wheel , gas, brake, and floor. its very difficult to drive with the air on when alone cause then when it starts making the loud noise and vibration I have to pull over to go under the dashboard to unplug it. especially with it getting cold is very hard. I would like to have my fan working right and to be able to use the knobs to turn the air and heat off and on..

My car has 140000 miles.
My car has an automatic transmission.