My central air conditioning unit seems to work well with normal air flow. On several occasions at night the inside coil has frozen allowing little air to pass. I have reset the thermostat to a higher setting allowing the coil to thaw and air flow returns to normal. The daytime temps have been in the mid 90's and the night temps have been in the 70's with average humidity for the Southwest. I seem to recall that this may mean the unit is low on freon. I would like your suggestions, and I will thank you in advance for your help!

Possibly low but maybe a dirty evaporator coil also.

My central air conditioning unit seems to work well with normal air flow. On several occasions at night the inside coil has frozen allowing little air to pass. I have reset the thermostat to a higher setting allowing the coil to thaw and air flow returns to normal. The daytime temps have been in the mid 90's and the night temps have been in the 70's with average humidity for the Southwest. I seem to recall that this may mean the unit is low on freon. I would like your suggestions, and I will thank you in advance for your help!!
First guess would be low charged