I agree, and mine is always covered in the winter to keep sun off the plastic, and to keep insects, bird droppings, and twigs out of it. Grumpy is right that it is designed to withstand rain and other elements, to a degree, but why not protect it during storage so it will last longer ? Even plastic wheel chocks have an expiration date that takes into account the adverse effects of sunlight and weather over time, so why not protect your A/C cover, just like tires, when you can ?
As to where you can get a cover, you need to measure the three dimensions of your A/C, and then shop for a cover that will accommodate those dimensions. Don't worry about the model number of the Coleman - just the dimensions. I ordered one for my A/C model, and it was too small. Used the dimensions next time, and came out OK.
2003 Ford F-350 V-10 Crew Cab 4WD Long Bed
2004 Jayco Designer Medallion 29 RLTS 5th wheel
Bill, Gayle, and Mindi (dachshund)
Retired at last !
Nothing is foolproof to a sufficiently talented fool.