APV means Arctic Power Valve. Cleaning depends on the oil that you are using. If you are using the Arctic Cat Powervalve oil (not to be confused with APV oil) then cleaning will be more often. The Powervalve oil was the 1st oil Cat came out with in 2000 (for the prototype). Once they switched over to the fully synthetic APV oil cleaning neede to be done half the time. Some people have found good luck using the Castrol R2 Synthetic Oil. Arctic Cat is really vague on this subject. In the Owners manual it states that APV system should be check & adjusted monthly. Bottom line is this:
Arctic Powervalves are not the easiest items to disassemble and clean. Try to pull on your cables. See if you can feel any binding. If not don't mess with it.
Powervalve oil between 1500-2000 miles
APV Oil 2500-3000 miles