2005 Dodge Caravan

Air Conditioning problem
2005 Dodge Caravan Automatic

for months my air conditioning controls would start blinking and the a/c would blow full blast even if the ac was off and the controls would lock up. Then after first cranking, the a/c would blow hot air out of the driver vents and cold air out of the passenger vents. Eventually a/c went out and dealer fixed under extended warranty but now the a/c still blows hot air out of one side and cold out of other side intermittenly. Dealer mechanic says it must be doing this when I bring it in for them to isolate the problem but by the time I get to Dealer, it is blowing cold again. This is wife's car and she is driving me crazy! Any ideas?