I use a braided poly rope, approximately 1/2 in thick and 50 foot long. A skinny one cuts into your hands, a thick one is easier to pull. Wear leather gloves to avoid rope burn.
It makes your day a lot safer and the work easier. We all need to go home uninjured at the end of the day.
By the way, always tie your ladder to the roof, the wind will blow your ladder down and leave you stranded or something damaged or someone killed. A friend lost his new job a week into it when the ladder blew over and damaged a car.
Some of my co-workers have placed a carabiner on an end of the rope.
My pump has a ring on the underside of the handle, it makes it easy to tie the rope to it.
A normal twisted type rope will untwist a little under load and cause the load to spin, a braided rope won't
When the rope is long enough, you can tie one end to your pump and another end to your refrigerant and scale. This way you can pull each load up individually and only make a single trip up. Leave the center of the rope tied to the top of the ladder or a rooftop object.
A bucket like home depot sells for $3.00 is useful for toting contactors, capacitors , liquid line driers and other minor parts up and bringing trash down.
I changed a 4 ton compressor on a roof on Friday. A co-worker and I hauled them up and down using ropes. I brought the recovery machine and tank up with a single trip, each was tied to a separate end of the rope., bring the middle up and pull one side up at a time. This will cut your trips in half.
Lowering equipment down, you can put the rope through any load that has a hole, such as a refrigerant tank, bucket or scale. Lower the load down with both lengths of the rope, not getting them tangled. When the load is on the next floor or ground you can toss one end to where it lies away from the load and pull the entire rope up through the hole in the load. This can save you a lot of trips up the ladder as long as you learn how to avoid getting the rope tangled.
I think a braided rope of sufficient thickness is a must have tool for anyone who climbs ladders and does rooftop work as part of their trade.