My AC keeps freezing up....clean ac vent, freon has been added, evaporator and condenser coils have been cleaned, all ducts have checked out ok., condensation line has been unclogged, etc. ...1st time the repair man added freon, and it still froze. 2nd time out he changed the capacitor on the furnace blower (it showed 3 and should have been a 5...so it needed it). However, it is still freezing ONLY at the outside line at the outside unit, not the evaporator coils. It runs fine for about 5 hours, then freezes at the outside line again. He wants to come and change the thermostat...but honestly, it cuts on and off just fine....thoughts? (I've read EVERYTHING on it but can't keep it from freezing). Typically freezing ac comes from either airflow problems or low freon....but those seem to be ruled out. Thanks.

If the outside is freezing, and not the inside, I would lean more towards the Freon level, not be properly charged or you have an issue with the valve inside your line sets

I should've asked is the fan on the outside unit spinning?

I'll be honest with you - if your AC guy is thinking the thermostat is causing this problem, then that means they are not understanding things well and you need to find someone else and have that person re-check the charge/operating pressures and check for airflow issues. You may also have a TXV acting up. A decent refrigeration tech can determine this looking at the pressures.

It was right at the lowest level of Freon and he added a little. I gave the outside coils a good cleaning (they were pretty dirty with old grass) and it's been running for 12 hours since and hasn't froze up since…so..maybe that wasn't allowing the proper heat exchange (maybe)…..keeping my fingers crossed that was it.

Exterior freeze up is majority of the time low freon

If your tech isn't checking superheat and subcool then he isn't able to properly diagnose what's wrong. Freon pressures don't tell enough of the story.

The thermostat could be an issue only because it is what tells the indoor fan to come on in the cooling mode. We've had more than a few Honeywell thermostats do dumb stuff like this.

What you need to listen for is the outdoor unit on and the indoor fan not on. Otherwise it's likely a refrigerant circuit issue such as a bad TXV.

Thank you for the reply.....it is a Honeywell thermostat. I personally feel the indoor furnace motor is NOT blowing as strong as it used too. He changed the capacitor on it...but it just doesn't have the "volume" of sound that it used to.