2000 Cadillac Deville Air Coditioning

Air Conditioning problem
2000 Cadillac Deville V8 Wheel Drive Type unknown Automatic 33121 miles

Gentlemen;
Since we purchased the aforementioned car, we have experienced a clicking noise under the driver's dash board, specially after starting the car. The first time (three years ago) it was repaired by the dealer at no cost to us. The car has been seating in the garage due to my spouse prolonged illness; however, I used the car from time to time to insure the battery does not die and allow the oil circulate throughout the engine. This past week, when I drove the car, I heard the same clicking noise. I took the car to to a a local repair shop and they told me that the repair of my car will require the removal of the entire dash port. The cost for the repair was estimated at @$850.00. A second expert in the A/C car repair estimated the repair at $1,500.00, and a third one to be at $1,800.00. I am so disappointed that such a wonderful machine made in the United States of America (at least I think so), with only 37,009 miles is giving me this recurring problems. Please let me know what route to take and the difficulty of repaireing such a problem if I purchase the proper manual.
Sincerely,
Luis