How long do I have to run the central AC in the winter to fry the compressor?

it will croak when it croaks. you need to ask yourself how much electricity you will use and pay for while hurrying it to the finish line. instead of trying for a new compressor thru insurance you should replace the whole unit and pay for it. a unit from the 80's is less than half as efficient as a new one . meaning your electric bill should actually be much less. sometimes you have to spend money to save money.

There are a number of safety devices that will shut the system down before that happens.

isn't that considered fraud?

Well, first of all, the warranty comp. is probably on to that scam. But, if you run it in the winter, it will be similar to operating a system in low load condition. The evaporator will not have enough heat energy from the return air passing over it to boil the refrigerant inside to reach 40 degrees. Probably 32d or lower. That will freeze up the evaporator coil into a giant ice ball. Then it will melt when you turn on the heat and get everything near the air handler and the copper line set wet. The condensation line may freeze the water if it's located near outdoor temperatures. Also, the compressor is supposed to pump vapor only, but refrigerant that doesn't boil into vapor is in liquid form now, inside the ecoil, and will ruin the valves, if it's a reciprocating type. If it's being serviced monthly, I'll guess it's leaking and being recharged, so it needs a thorough leak check and repair, up to 500 bucks. Will they buy another 13 seer to replace it ? or a higher seer but they may not pay for difference, that should be written out. Then, they may not pay for install labor, up to 500 again. If it were me, I'd shop for a deal this time of year and buy a 16 seer or higher and research State rebates, Federal credits, manufacturer discounts, and have a warranty on a new system

The compressor has a heater in it to keep the lubricating oil from congealing - it doesn't care if it's winter or summer. 1) some insurance that covers normal wear-and-tear !! 2) somethings wrong if it needs service every month - - - according to records our central air was installed around 1986: it has never been serviced and can freeze us out in the hottest weather.

you might not get a new unit just a comp replacement. teach your dog to piss on the condensor coil that will ruin it and you can even assit in this but you should do it at night

no it will just have to wear out, turn it on and let it run