Even if the fan does not run off of the IMA, the battery should not deplete by 50% overnight and indicates charge retention problems. Battery pack replacement seems necessary. In addition, if the A/C does not blow cold, something is definitely wrong with the system itself.

One thing I forgot to mention: If you push the ECON button on the center console so that the green LED is lit, Auto-Stop is activated. During Auto-Stop, which is when the car's engine turns off at stoplights/stop signs, the A/C compressor is deactivated. But once your engine turns back on, the A/C compressor should start again and blow cold.

The car in question is a 2003 Honda Civic Hybrid, generation 1.

Unlike your 2007 Honda Civic Hybrid, generation 2, the generation 1 HCH's A/C does not run off of the IMA. Please take care to check what model year the HCH is before answering questions, lest we confuse the new owner even more!

Thanks!