I found recently that my battery would not stay charged over night. One evening while in the garage I heard the old, squeaky heater fan running even when the key was not in the ignition!
I figured this was the cause of the draw so I replaced the heater fan and all was well for a week, then it started again. The battery will loose charge overnight.
When I hook up booster cable to the battery, the heater fan will start running and the lights on the heater head unit will come on, even when the key is not in the ignition.
I think the spirit of Christine has possessed my car!!
Can anyone give me an idea of where I should be looking now to find the source of the draw?

With the key off the blower motor should not have power. You will need to start pulling fuses or look up the HVAC circuit and pull that one. Now you have narrowed it down to that circuit,

this should be moved to electrical.

You could pull fuses for the HVAC system.

But I assume you have the automatic control AC. The blower control modules sometimes go bad and work part time, change blower speeds oddly and at random, and sometimes keep the blower runnin even when the key is off.

Blower control modules are available in aftermarket at Advanced Auto, e.g. Here'* the location. One or two bolts hold the relay center above it and it can be raised up a little giving room.

Stupid question. You are saying blower control module, but showing a picture of the resistor assembly. Are they the same?

They are in the same location. This is the only picture I could find that I had saved in my photobucket. Grin.

It might be worth disconnecting the power at the blower control module to see if that makes a difference.

First off, thanks for the tip on the module.

So I put in another blower control module from another car that was working fine. I hooked up the battery and the lights on the head unit in the car came on right away before I could even start the car. I started the car and the heater was in auto mode, but the fan didn't come on. I turned the fan speed up and down which worked fine. I shut off the car and took out the key, but the lights on the head unit stayed on. As I stood in front of the car scratching my head, the blower fan kicked on high. I had to disconnect the battery to shut it off. Any other ideas?

I've got EXACTLY the same problem on my '97 SSEi and haven't figured it out yet. Maybe something grounded out?