[calflan]

Recently a few times have had the Air Conditioning lines freeze up from and to the condenser. At the time was running floor and defrost flow on more warmer selection than cold and after about an hour or so, flow from the ducts dropped to nearly nothing. Selected upper vents and no flwo from them. Looked under the hood and noticed the lines covered with ice and frost. After the car sat about 20 minutes, the lines defrosted and the flow was back when driving again. Seems this happens when the defrost mode or the mixed defrost / floor mode is selected.

This is happening more and more frequent now and taking less time to happen (originally was 1 hr., now about 30-40 minutes).

Why would these lines be freezing and how do they control flow from the distribustion system ?
Thanks.