I'm not a soda machine compressor expert, but most AC systems freeze up when they are LOW on freon.
That’s because they run R22 ( newer systems R410 or other R22 replacement) , it has a much higher system pressure but a lower temperature glide, an HVAC system is a medium/high temperature application really designed for dehumidification of the home, it operates well above freezing. but when there’s a leak & lower pressure at the evaporator the R22 will quickly slip below 32-F & ice over the coils.
So as the pressure in the system drops, the temperature at the evaporator actually gets colder, but there’s less gas in the system to absorb the heat from the passing air, so an under charged refrigeration system will tend to only frost up at the end where the capillary tube enters the larger evaporator tubing, on an overcharged system the freon doesn’t begin to transition back to a gas until it’s well towards the end of the evaporator coils ( a flooded evaporator) usually leading to the suction line icing as well, sometimes all the way back down to the compressor,
The added service value & the spare can of freon I see leads me to believe that it had a leak or someone thought it was low on freon & the system was recharged & possibly over charged in the process if the person adding R12 to the system didn’t use a scale or otherwise install the correct charge.
