[dutchmensport]

There are many folks who use the compressed air blow method only and are very successful with this process. I've never taken notice if anyone who does the blow exclusively process lives in Canada or the Northern States in the US. The reason I state this is because, if you live in the Southern states and blow only, you can most assuredly get away with it. A few hours of below freezing weather and then it warms up again is far different than when temperatures get to zero and below, and stay there for days and days on end.

Regardless of how much you "blow" the lines, there are still particles of water droplets that will remain in the water lines. Now, considering the lines are virtually empty, a short term freeze probably won't even reach the lines inside the camper. But a long term hard freeze eventually will. I've forgotten the dogs water bowl sometimes, and with all the heat off and the trailer shut down, and the outside temperatures are 20 degrees or less long enough, that dog bowl will turn to solid ice inside the camper. Any residual water droplets do too.

Now, residual water droplets in a virtually empty water line have lots of room to expand and not hurt anything. But, the residual water drops that remain around your valves, your faucet valves, and any other valve, even the slightest amount of water vapor left in them will also freeze, expand and potentially damage the seal. Regardless of how hard you try, when using the compressed air only method, there is still always some water remaining in the lines. Mostly it doesn't hurt, but it only takes that one time for some unwelcome repairs will be needed in the Spring.

So, if you live in a "hard freeze" zone, I suggest you do not depend on the compressed air method only.

When I winterize, I pump the pink first. This replaces all the water. I then blow the pink out with the compressor. This keeps the pink stuff from tainting the water lines so much, but does replace all the water, 100%.

That's my suggestion. There are no right or wrong ways to do it, we all do it different for different reasons and we do it different depending upon where we live and how the camper is stored (or used) over the cold months.