Air Conditioning - Outside AC not coming on

I hope someone can help. I tried turning on my AC yesterday and nothing happened. When I turned on the AC through the thermostat, the inside fan started running, but no cold air was coming out of the vents. I went outside and the air conditioner was not on and the fan on the air conditioner was not turning. I read a little bit about the parts of the AC on the internet. I first checked the fuse box inside the house. The fuse is fine. I opened the air conditioner panel and had my mom switch the thermostat back to the on position for AC. I could see this button move on the AC control panel and then there was a humming. When my mom shut off the thermostat, the button popped back out. Now, I believe what I was looking at was the contactor. I understand that you can manually push a button on the contactor with something non metallic to see if the AC will start manually. My question is where is this button. Was the button the thing that switched on and off when my mom adjusted the thermostat? If so, then I guess it is working. Otherwise, if it is somewhere else, if someone could please tell me the location on the contactor so I can push it manually. If someone can deduce what the problem is from my explanation, any help would be great.

On a side note. I turned the fan manually, but it still did not start. I have a Lennox air conditioner. Not sure about the model, but it is about 10 yrs old.

Thanks in advance.

Oreo9

Ok, if the contactor is pulling in, then the low voltage is ok.

Did you check the disconnect switch on the side of the house going to the unit?? some time there is a breaker/fuse... Check make sure they are ok.

Check to see if you are getting 220 volts to the contacter.. Some time the points may have spider nest or bug.. make sure that is clean.. TURN OFF POWER!