Definitely cable TV wiring. 

Then you want to figure out all the typical short term rental expenses (furnishings, cable, internet, utilities, possibly management) and factor in your mortgage and heloc payment.This should give you a good idea of your yearly and monthly profit

So I guesstimated the bills ...electric , gas , water and cable.  

On HOA fees... yes, they can be a huge expense but... they often cover expenses like building insurance, grounds upkeep, pools, lazy rivers, beach access, cable, water and trash.

The master bedroom got a fan box and 14-3 cable from the switch to the box when the wiring was done, so it wouldn't be a lot of extra work.

Monthly Operating Expenses 2,208.33Net Operating Income (NOI)Total Gross Annual Operating Income 65,280.00 Total Gross Annual Operating Expense 26,500.00 Annual Net Operating Income 38,780.00 CAP RATE and VALUATIONDesired Capitalization Rate6.27%Property Valuation (Offer Price) 618,500.80 Actual Purchase Price 749,900.00 Actual Capitalization Rate5.17%SHORT TERM RENTALMONTHLY OPERATING INCOMESTRNumber of Units 8 Average Monthly Rent per Unit - STR 2,000.00 very modest estimate Gross Monthly Operating Income 16,000.00 MONTHLY OPERATING EXPENSEProperty Management Fees 600.00 Repairs and Maintenance 1,000.00 Real Estate Taxes 2018 records 1,095.00 Rental Property Insurance 480.00 Homeowners/Property Association Fees Replacement Reserve 51.00 Utilities - Electrical, gas, trash, water sewage, internet, cable 4,080.00 Pest Control?

Appears that some sort of wire or cable may have went through the baseboard and was excessively hot/caught fire at some point. 

When I purchased, my mortgage was around $1,650 and the HOA fee was $515/month including cable/internet.

Each type of asset has different requirements especially commercial vs residential but overall the process looks like this for commercial or multi family:Check with the city or county to determine what is required for all approvals including site plan and building permits, proffers, water/sewer tap fees, bonding requirements, inspections and CO process and time frame for all approvals.You also need to check with the utility companies and get an idea of availability and cost estimates from them for water, sewer, power, gas, cable, installation and connection requirements, tap fees, hookup charges, transformer location and relocation, power line and power pole relocation issues.Check to see if you have to install any manholes,fire hydrants, curb, gutter, sidewalks, street signs, street lighting any specific street design or access requirements,.Check DOT requirements for access, stop lights and permits, traffic studiesDWQ requirements for permits, permit fees, time framesThis is a broad overview of the process and your civil engineer can handle all of this but it's good for you to know exactly what's required.Residential is much easier but similar considerations.

The fix for that is usually shutting off the power at the box on the side of the house where the cable from the A/C connects, hosing it out with a garden hose (use a wide spray nozzle rather than a thin "laser beam" of water, so you don't bend up the fins on the condenser), letting it dry out for a couple of hours, and then turning the power back on.