It sounds as though the system needs a recharge. Since it's sporadic like you are talking about, it seems one of the pressures the system reads for is out of bounds (low in this case) during operation, which shuts the system down (the compressor is turned off) which causes the cold air not to flow. As soon as the system equalizes and pressures go up on the low side, the system cuts back in and it will cool for a little bit until things get out of bounds again.
If this is what the issue is, it doesn't mean your system has a real issue (other than needing more refrigerant). If you don't use your A/C system regularly, it can lose refrigerant past the seals ... just a fact of life. It should just need the recharge and with regular usage be good to go.
I'm not sure if you have the means in your location to recharge this on your own, but would suggest if you have never messed with an A/C system before to take it somewhere and have them do it for you. Taking it to a place which specializes in A/C repairs is going to be your best bet.