Rooftop ac coolant recharge

[Tonijim]

Our 2010 Class C rooftop ac unit is operating just marginally. I've been told that they are "sealed units" and to recharge their freon coolant is tough. Who has had this work done and what has been the experience?

Thanks, Jim

[Sam_Spade]

You are just guessing that the drop in performance is due to low coolant.
That may not be the case at all.

Maybe you should be asking for recommendations for a good vehicle A/C shop in your area......because I think this really requires a professional diagnosis.

Even if the coolant IS low, you need to find the leak and fix it or it's just a waste of time and money.

[j-d]

They don't leak down all that often.
Before you assume it needs refrigerant:

Are the Coils clean? The Condenser coil on the rear of the unit is easy. The Evaporator is under a sheet metal cover on the front of the unit.

Is the Filter clean?

If it's Ducted, are you sure there isn't a problem in the ducting? Likely where the A/C is installed.

Are you running it on High Fan, reducing the chance of the Evaporator Coil frosting over? If your unit is Ducted, a Freeze Sensor will detect that and stop the compressor from further cooling till it's satisfied the coil isn't freezing. If it's not ducted, freeze over will reduce, probably stop, cooling.