Bookworm wrong...........wrong ..........wrong
carb heat CAN cause icing in the venturi of the carb and starve the engine of fuel. air below 0 degrees still has a moisture content. However its frozen and will not adhere to the carb venturi, fuel jet etc but bounce straight through, but..... heat that air to just above freezing and the moisture will then freeze as it goes through the venturi (remeber the theory :- increase velocity and temperature decreases ) when it freezes the moisture will then adhere to the inside of that carb.... guarenteed.
basically it the oat is below -5 degrees putting carb heat will probably not hurt, but above that to about +5 degrees, wow you could be in trouble, Honest, dont try this in the air folks........
