I have had this problem for a while, but at first when I would turn the heat or air on, it would make a "knocking" noise for about a minute. Also, a noise as if the air/heat was trying to differentiate between the defrost or heat. Now, I have had to replace two batteries because I have had to keep getting jump-offs, Also, it seems to be an electrical problem because the signal light, trunk, and several other functions dont start working until I have driven the car for about 20-30 min. Someone told me it could be the blend door actuator. What is causing my battery to die and why am I having the electrical problems. Sorry for the long message.

I you are still mobile, go to one of the chain auto parts stores and ask them to load test your battery. If it looks OK, you may have a leaky diode in the alternator that is slowly draining the battery when the car is at rest. They can also check the alternator but it may have to be disconnected for that and I'm not sure that is free.
There is a simple test you can do with most multimeters since they nearly all have a separate jack for 10A but this is not protected so never put it across the battery with it connected that way. What can be done with it though is check for leakage current when the car and ALL accessories are turned off. Disconnect the negative (-) battery terminal, put the red/positive meter lead that should be connected to the 10A jack on the meter on the clamp, not the battery terminal, then the negative/black lead on the negative battery terminal. The meter will be marked to show which position the knob of the meter must be for the 10A range. Cheap meters can show 3 1/2 digits so full range on the 10A range can show 10.01 or a little more, it depends on the meter. With everything switched off that you can, you should see nearly nothing on the display or at least less than 00.05 which is 5 thousandths of an amp. This would OK since there are devices in any later car that are always 'On' that draw a little current. If it is over 01.XX, this could drain a battery in 20-30- hours unless very new and fully charged.
You can buy such a digital meter for under $20 US at auto parts stores, Radio Shack, etc. DON"T pay more, you don't need a very accurate meter or any bells and whistles and you will find uses for it around home too. They normally come with some kind of Chinglish instructions which may be intelligible enough for most.