Cadillac Repair: 1998 deville ac problem, dash vents, circuitboard

Question
Bill,
I recently bought a 1998 Deville with a 4.6 Northstar. The a/c will sometimes start blowing out of the defroster instead of dash vents. It lasts for only a minute or two and then returns through the dash vents. At first it was rare, but now is happening more often. Sometimes the problem can be solved by turning the ac off and then back on. The air always remains cold when coming out of either vents. Any ideas?
Thank you,
Adam

Answer
Hi Adam,

     I have not experienced this problem firsthand. It would seem like a module or circuitboard problem but there are 3 things that would fit that description.

     The best thing to do would be to have your mechanic check it out when it is acting up so the right part gets replaced. Sorry I can't be anymore help than that. Bill