Cadillac: Air conditioner blower, 1990 cadillac seville, air conditioner blower

Question
1990 Cadillac Seville-------------------------------------------
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The air conditioner blower continues to run after engine is shut off. Is this a common problem and where do I start troubleshooting?  I have to disconnect the battery when I shutdown.
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YEAR and MODEL ?

Answer
There are numerous pictures and diagnostic procedures that must be tested to determine which of the below items is at fault:

1. BCM (computer).
2. Power Module.
3. AC/Heater programmer.

Most likely the fault is the power module in most cases, But the tests should be performed.

The power module is located just above and to the left of the blower motor on top of the black plastic housing. It has 2 electrical connectors attached to it and is held on by 2 7mm screws. When you remove it, you will see a big aluminum finned component attached to the bottom of it.