Read about them here: http://www.newair.com/articles/oil-filled-heaters/------HEATING, COOLING, AND VENTILATION SYSTEMS.Landlord agrees to maintain heating, cooling and ventilation systems on premises that are provided by Landlord.Tenant agrees to notify Landlord in a timely manner, and in writing, of any problems that arise with these systems.Tenant agrees to keep heating and cooling systems in good working order and to take safety precautions in accordance with their use, following manufacturer and fire department recommendations.a.Natural Gas furnace system:Tenant will not store items in the furnace closet, except for replacement filters.Tenant will allow Landlord to replace furnace filters when Landlord determines it necessary.Tenant agrees not to block air ducts (warm air output and cold air return) and to pay for any damage to the heating system caused by failure to do so.b.Electric baseboard and wall fan heaters:Tenant agrees not to block the heaters, to keep all flammable materials at least one foot from the heating device and to maintain ample air flow around heater.

Add a ventilation fan to the laundry area and/or forced air flow, to help keep the moisture down.6.

If you want to take the DIY method for it, bring it home, stack it with little boards in between it for airflow, tarp it and set off 3-4 bug bombs under the tarp.  

Freezing up usually points to a couple issues: 1) dirty filter on the indoor or outdoor unit so it doesn't get the airflow it needs to transfer the heat or 2) low refrigerant.

Common sense indicates that 1. it's a fire hazard and 2. it's restricting the airflow and probably caused the overheating.I called the repair place and talked to the tech, he confirmed that the cardboard was there when he showed up, so at least the tenant can't claim he just happened to put it there yesterday.

This sealed off the dust, and gives a grand storage/workshop area,   HOWEVER, it also sealed off the airflow, with the result that any dampness wicking through from the outside soil makes any nearby surface mold heaven.

Cut them trees away from the house - you need air flow to keep this stuff from staying damp. 

Good Ole Clorox seems to work, be sure to wear a breathing mask when applying as well as get some good air flow and circulation.I know Home Depot sells something for like 30 bucks called "Mold Control" it has you mix two containers into an spray bottle.

I have a flu that does not seal well on a fireplace.  I have a gas log that I am pretty sure does not need a vent.I can feel a draft up the chimney.  What would be an inexpensive way to seal it?  I still would like to...

The system has to heat the whole building and even if you to 'isolate' the non-occupied units, the heat will still migrate there via air flow or simple conduction.