Infants open air conditioning runny nose may be caused by hot and cold air stimulation, or infant colds, dust mite allergies and other diseases. 1. Hot and cold air stimulation: because of the baby’s age, the development of organs and functions is not yet mature, the peripheral nerves of the nasal mucosa is more sensitive, so the air conditioning issued by the hot and cold air on the nasal glands caused by the stimulation, and then there will be a runny nose. 2. Infant cold: this disease is mostly caused by rhinovirus, respiratory syncytial virus, parainfluenza virus and other viral infections, and in a few cases, it is caused by bacterial infections, which are often triggered by temperature changes, poor ventilation, immunity decline, catching a cold, etc., leading to nasal congestion, runny nose, dry cough and other symptoms, which can be manifested as running nose when the air conditioner is turned on in infants. 3. Dust mite allergy: the occurrence of this disease is related to family history of allergy, contact with dust mites, immunity slightly lower children and other factors. It can be manifested in the infant air conditioning runny nose. Infants open air conditioning runny nose may also have other causes, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.