Most small dealers track air conditioners by model: twelve 1.5-ton inverters, nine 1-ton. It works until a customer returns six months later and says the unit stopped cooling.
Three questions a model count cannot answer
Which unit was it? Is it still under warranty? What did it cost you?
With a serial record, each answer is a search away. The unit shows who sold it, on what date, when the warranty ends, and what you paid.
What a unit record holds
A status (in stock, sold, in repair, returned), every movement it has made between locations, and, if you allow your staff to see it, its cost. Indoor and outdoor halves can be grouped as one set so they are sold and warranted together.
It is cheaper than it sounds
Serials are scanned when stock is received and when it is sold. The scanner does the typing. The payoff is that warranty claims, stock counts and returns stop being arguments.