Speaking generally about automobile A/C systems, there are two main modes, normal and recirculate. Normal draws warm, humid outside over the evaporator coils and into the car. When using recirculate cooler, dryer interior air is drawn in from the vehicle cabin instead of outside.
The question is: During hot summer days, which mode is more likely to cause the evaporator to ice up?
Some say recirculate is more likely to cause evaporator icing because the cooler air in the cabin doesn't have enough heat to keep the condensate build-up from freezing, but the cabin air has already been dried and thus has much less moisture to condense in the first place.
Others say normal mode is more likely to cause icing because it is drawing in the much more humid outside air that will subsequently cause more condensate and thus more chance of icing. On the other hand outside air is much warmer and that heat is perhaps enough to keep the condensate above freezing.
Note that in a properly designed system there should be minimal, if any, icing. This question is more about exploring when the A/C is pushed to its limits or starting to malfunction, which mode will cause icing first.
Also note that this question mainly pertains to the use of A/C on warm summer days to cool the interior of the car, not the use of the A/C to dry the air on a cold, wet day.
