Explorer Climate Control continuously clicking
 

I have a 2000 ExplorerEddie Bauer with the Auto Climate Control. It has clickingsound that comes from the dashboard aboutonce a second. The clicking sound is less with the temperature setting in the 70's (outside temp is in the mid 70's),but increases in intensity (almost a thumping sound) when the temperature issetin the80's orin the 60's. It appears to be working but I have not checked the temperature of the air blowing out compared to the temperature setting.The sound does stop when the climate control is turned off.

Anyone have any ideas or experienceon what the problem might be?