That looks like the connection for a four prong relay. Look under your hood and you will see what a four prong relay is supposed to look like.

See if one of the holes is to ground all the time. Then check for 12v at one of the poles when the ignitions is on. If so you have a plug for a relay.

Now the question is, if it is a relay connection, where do the other two wires come from and where to they go? Since this is in the air conditioner area I would guess this might go to a high or low pressure cut off switch next to your air conditioner dryer. But that is just a guess.