Climate Control problem
 

I am having intermitent problems with the climate control on my 1996 Deville. The heater comes on automatically, and eventually all the characters on the dash board turn into dashes. A message sometimes appears "The theft security system is activated, car may not re-start", but so far it has restarted. I can go for a couple days or so and it is normal, then is happens again.
What can this be?

Codes?

That would usually clear any blockage in the block and heater area. If they did, it makes no sense that they do it 3 to 4 times which is already suspect. Also raising the front end of the vehicle to remove air bubbles sounds like something click and clack would do.
One thing you could do now is to check the overflow tank and make sure it is at least filled to the cold line. If it is then check the radiator to see if it is topped off. Please do this when the motor is cold.
Other than that you may want to change mechanics.

pz2255 (from pressing the off & warm buttons at the same time)