AC electrical question

Needs some help figuring this out. AC system installed in 2012. In checking the panel I see a single pole 20 amp breaker labeled AC with a 6 gauge wire jammed in it. I traced the AC cable coming in to the panel, it is a 3 wire system, hot, neutral, ground. I am thinking the AC needs a 240v 2 pole breaker with 2 hots and ground, what I have been seeing until now. I did not operate the system, too cold yet. How is this system working? Or not? What are the ramifications from this? would the system run but not cool?

I can not see what you see from here but I can tell you the compressor and outdoor fan motor operate from a double pole breaker that measures 120 volts to ground on each leg and 240 volts between the two legs. There is no neutral just an equipment ground. Your Data plate says max circuit breaker 25 amps and that would be correct for a two ton unit.

I think that you got the wrong cable for the AC.

Sounds like a 120 volt system .

Perhaps, but it is labeled 1st floor AC. Here are some more pics of the panel. The wiring I am referencing is the one coming in from the lower left, runs along the bottom of the panel.

I only see one pole breaker, one leg not two.

Can any one tell me why my photos are converting back when I upload them? Do I need to change some sort of setting on my computer? This only started when I got a new computer.

I see a #6 on the breaker and one that looks the same on the Neutral buss.
Right next to each other at the bottom of the panel.

I think your looking at the wrong wire.
Only 120vac needed for a furnace. Condensing unit on another circuit.

Something is miss labeled or your looking at the wrong wire

OK thanks for the help. You are probably right. Legend was incomplete but the breaker was labeled AC, hence the confusion on my part.

Did you also notice a couple of branch circuits with cloth wiring? We flag that stuff in Florida.

The label first floor AC may have been from a window unit from prior years. Do not believe labeling. Plus it is outside the scope of a a home inspection to verify labeling.