Had a ideer for a A/C system

Okay so I had done some looking before in regards to something like this and I stumbled on a instructable.com article. The guy had used a sump pump in a ice chest filled with ice and water and a 12 volt fan out the top with a heater core below it. The pump would push water through the heater core and the fan would suck cold air while another would push warm air.

I had thought about the design and came up with a slightly better idea which also would work. You use the same idea but instead use some hard insulation under the heater core and above the ice. This would allow the ice to stay cold longer. Furthermore you could go further and use the heater core and fan in our cars. One issue with this though is condensation on the heater core would need some place to go.

I like the idea of simply fill a cooler with some ice and water and cooling the car. The guy claimed he could reduce the ambient temp 30 degrees in a few minutes. Also to drop the temp of the ice water add some salt. I am not sure how well the salt will work with the heater core though.