What caused my crack to form?
Normally a crack is formed by a rockchip that was not repaired or went unnoticed. It could also have been created upon direct impact from an object. When the windshield is Hot and Cold water or Cold air from your air conditioner comes in contact with the windshield, it may cause thermal expansion causing the rockchip to turn into a crack. The opposite is true. When the windshield is Cold (ex. ice on the windshield) and Hot water or Hot air from your Heater/Defroster comes in contact with the windshield a crack may form.