Air Conditioning problem
1989 Cadillac Seville 4 cyl Front Wheel Drive Automatic 75000 miles

I have had the "A'c compressor off/ low compressor" message on my console or a few days, and was planning on having it charged or checked out later this week.
As I drove it today the blower motor turned on, and won't turn off.

I have read about problems with the 89 Seville's compressor sensor, and blower motor on other forums, but they talk about it turning being off. How can I get it to turn off? I know this will be a severe drain on the battery, and cause wear to the other parts of the AC system. I have seen fixes for those issues, but what can I do from home before I send it off to the shop?

Incedentally I have arleady replaced the tempreture sensor and a blower component when I bought it, so could this be a fault in the electrical system causing faulty readings or triggers?