Gas and Oil Home Heating Furnaces - A/C water supply?

I bought an older home with a Coleman central A/C unit outside. It has some weird coils and a 16"x4" diameter thing connected that looks like it might contain freon? Anyways, it works, but there is a 1/4" copper water line going to the unit from a shared water line with my garden sprinklers, that when the A/C is on, my sprinklers are leaking water. Is it that my sprinkler valve is just old and needs better gaskets, or is the A/C applying too much pressure in the water line? What does the A/C need with the water supply? Thanks for any advice.

have a water cooled condenser. does the outdoor unit have a fan? possibly need a check valve, more info needed....model#, mfr, age. etc

Thanks for your interest and reply hvac4u. The unit outside is a standard looking A/C compressor with the large fan, etc. It is a Coleman model 9548-901, probably 15+ years old. But it does have those extra coils and the cylinder I mentioned in the original post. I have noticed that there appears to be a drain pipe coming to the outside from somewhere in the wall...maybe from the condensor? The water supply appears to go up into the house through a "Refrigerant Filter Drier" toward the condensor, I guess. I haven't seen any water coming from the drain, but I never ran the A/C for more than an hour yet. I wonder if the inline filter is clogged? Causing pressure to force water through my sprinkler? Very weird setup. I guess I'll have it serviced to get the scoop.

Nervouse, from what you've mentioned, at first it sounded like a water to air heat pump but then again there's too many unknowns. Thats not the case if the outside unit has a condenser fan. Perhaps someone jury rigged something for humidification, taking water from the sprinkler. Be best you call an HVAC tech and let him figure it out for you.

Just wanted to let who ever is interested, that my A/C unit is from 1976 and it has a water cooled "pre-cooler" for the freon, thus the input and exhaust of water (into my sprinkler line so it comes out the sprinkler heads) as it circulates around the freon tubing in the coil I previously mentioned. Really energy inefficient (electricity and water). I am seeking bids now to replace it.