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This history lesson will help techs know how and when to use these parts, but it can also be of value to shop foremen and writers trying to accurately estimate the cost of a repair AND see what options exist, since a lot of this research can be done from a desk.
Understanding some of the history of a/c implementation in vehicles helps you understand just when it’s appropriate to recommend one to your customers. There’s a chronological history of how mechanics have dealt with a compressor that’s going to be removed from the accessory drive system, and the solution has gotten more complex as vehicles have, as well. Knowing the history helps you write the cheapest estimate for the customer in the least amount of time.
Dorman sells A/C bypass pulleys, of course, but you might not need one. My education on these began when I was selling them across a counter. I started slinging parts as a counterman in 2002, and by the time a vehicle is old enough that it has an owner who makes his own repairs and shopping at an auto parts store, it’s at least ten years old and often much older, so I got to see a fair cross-section of vehicles of varying age.
A word of caution, though, first. The A/C system is often used even in the winter to prevent fogging in Defrost mode by dehumidifying the air. It can be an integral part of the high voltage battery and component cooling system on hybrids and EVs.