Antihistamines, H1. Histamine antagonists or antihistamines are drugs that relieve allergy symptoms.Histamine is a chemical used to identify and remove substances that trigger an allergic response. Ã¢ There are four histamine receptors &#40;designated H<sub>1</sub>, H<sub>2</sub>, H<sub>3</sub>, H<sub>4</sub>&#41;.
Quick Answer. Blocked condensation drain lines often cause excessive amounts of water in an air conditioner drain pan. These lines are designed to funnel excess water from condensation away from the air conditioning system inside the home. If these lines become blocked, the excess water drains into a drain pan.
Freon Leak. Another reason for air conditioner freeze up is the lack of coolant. However, if your air conditioner is low on freon that is not a normal condition that occurs over time. If the air conditioning unit has leaked coolant and the levels are low, the air conditioning system works harder than normal and can form ice on the coils and pipes.