I've been battling an AC condenser freezing up for the past 2 years. 

One of my subs just replaced his AC condenser--just the unit, no line set, etc and it was $2650 as a "softball coach special" so it is pretty easy to guess you will be in the 3K range. 

She only did maintenance, but did replace the roof and AC condenser after the fires in 2016 (insurance paid).

The condenser is in a corner of the backyard.

Once about 10 years ago our tenant did not install their unit correctly and the water condensation was dripping into the house and actually caused part of the ceiling to collapse.  

that all works until your condenser is stolen right ? 

Then you can clean/remove the mold and the problem won't come back.The most common source of moisture is lack of ventilation in the bathrooms or condensation on windows in the winter.

Having a weird plug like this reduces the chance of the outlet being used for other purposes.3) Many of the travel chargers are nominally waterproof, but in practice need to be sheltered to avoid internal condensation.

For small spaces, you can't get a small enough (in terms of BTU) multi-zone unit and what happens is one unit receives refrigerant even when not running if the other is running, which due to the cold of the evap coil causes it to condensate and ultimately causes constant problems with drainage.Also, look for a mini-split where you can connect an external thermostat and configure the head unit to shut off when the set point is reached.

However, if the furnace is 20+ years old and likely to need to be replaced soon, I'll go ahead and replace the unit and get a new unit with air (evaporated coil and condenser).