We have been having on going intermittant issues with our air conditioning. Sometimes it works fine and blows out cold air when turned down low. Often though it will be blowing ice cold air on two of the vents on one side of the car and warmer air through the other two vents. the sides do sometimes swap around as well. when the temp is turned up it will blow hot air one side and cooler air on the other. the actual pressure of the air is less on the side that is not working properly as well.

Our local ford dealer has had the car in many times during the last two years ( the issue occured whilst still under warranty) and have replaced pretty much the entire air con system, compressor, vents, control panel etc. They now seem stumped as to what could be causing it. As the air con does work at certain times we think the actual system must be ok as it will blow out air around 6 degrees C. Does anyone have any ideas of what would cause this fault?

Many thanks