Baffling a/c thermostat electric issue, need help

[Skykingrob]

I am trying to get temporary air conditioning in my unit so I can work. It is still 96 degrees and 80% humidity which I have struggled with all summer but I am tired of it.
I have a basement a/c unit that runs off 110 volt power. I have a heavy extension cord, good enough for 30 amps but the unit only requires 15-20 amps, to run this and it runs fine when the thermostat allows it to. The thermostat is 12 volt and must be "on" to allow the 110 volt to power the unit. I am trying to power the thermostat from a 12 volt deep cycle battery, but whenever I connect the 12 volt battery to the thermostat, it blows the 2 amp fuse and cuts off power to the thermostat, thus stopping power getting to the unit. Most of the time the fuse blows immediately, once it ran the unit for a week before it blew. Since this one time of a week, the fuses have blown immediately. The fuse that came in the thermostat is a 2 amp/250 VP. Since I have none of those available, I went to an auto store and bought 2 amp AGC fuses. I am wondering if this is the problem. Tonight, in desperation, I tried powering the thermostat from a 1 amp battery charger and it still blew the fuse immediately.
I will eventually wire everything in like it is suppose to but right now I need temporary relief.
What am I missing here and how best to accomplish what I want to do?

Rob
91 Prevost LeMirage XL
Missouri

[artvonne]

  In the mean time..... you could just take out the T-stat and hot wire the AC to run continuously. then, you can play with the T-stat in your spare time after your done working on Da Bus. If it gets too cold you could crack a window. Sounds like a relay problem to me, thats about the only thing that could switch 120 volts from a 12 volt source. Its been so warm, and I found out Missouri is about the most humid place on Earth, I doubt the AC would cycle anyway. 

[JWallin]

The thermostat and the relay in the unit needs 12 volts ac to operate.