You can blow the air conditioner in summer when you have a cold, but you need to take precautions.
If the weather is too hot in summer, you can blow the air conditioner, otherwise, the high temperature may cause discomfort to the body and may even lead to heat stroke and other related complications.
Although air conditioning may cause colds in summer, it may make your body more comfortable if you take proper precautions, which may have a certain effect on your recovery. For example, the temperature of the air conditioner should not be too low and you should not blow directly into the air conditioner when you have a cold in summer.
To summarize, it is incorrect to say that you should not blow the air conditioner when you have a cold in summer.